How does lords deity in the temple installed ?

There are certain laws promulgated on various administrative measures. Based on that laws rules/procedures framed thereof. The rules may slightly vary according to the organizations but without violating any thing prescribed under the law and rules. Similarly there are certain procedures and formalities prescribed for constructing the temples, installing idols etc which is called 'aagama vidhi'. No violations from the vidhi can be found and if any violation the result will be indicated instantly. As of the respective law/rules/procedures known only by lawyers and concerned dealing persons, these aagama vidhis are known to the persons related to the temple construction.

In Hinduism, Pranpratishtha is a ritual in which a murthi or deity is established in a temple and consecrated with recitation of mantras to invite the deity to live there. Hindu people worship of different god for different things/quality/occasion like worship Goddess Laxmi or wealth, Goddess Saraswathi for education, Goddess Durga for Power and so on. And starting of every puja is done with the worship of Lord Ganesha. Lord Rama, Lord Krishna, Lord Hanuman are all human forms God.

But all these murthi are created by human being as hindu believe and imagine a human like God and hence they believe in the murthi with life. But the main thing is that the murthi is created by God but that is believed to be more powerful than the humans. The main motive of this ritual (Pranpratistha) is to invite the deity to initiate life in the murthi created by human being and to make it more powerful. Pranpratishtha means consecrated life or bringing life.

To invite lord to live in the deity there are several ways. Recitation/ chanting of Sanskrit Mantras is the most common and popular way of inviting deity to a murthi in a temple and live as a guest.

In Jainism there is a similar ritual of Abhisheka of Jina statue, wherein they pour the deity with auspicious liquid like water or milk and consecrated the statue. The ritual is called eye-opening.

The ritual can be performed by Pandit, Pujari, Guru or swami in temple.

Generally the Gods will have an 'idol', for example, Ganesha, Lakshmi or Shiva etc. These images help the Hindus to concentrate on various aspects by taking the idol as the form of a particular God . Each shrine will have a puja tray containing seven items. These items are used in worship. There will be five senses also i,e, sight, smell, touch, taste and sound to complete the puja.
There are two main ways of worshiping God, Suguna and Nir gun, Rupa and Nirakara. Generally it is assume that who are nearer to God (Monk) takes the Nir gun/Nirakar way and others family man takes the Suguna or Rupa to pray. As per Yajurveda it has been said that "Na Tasia Pratima Asti" i, e, it is not essential and without Idol puja can be done. Only Purohit can do this puja on behalf of every one but Individual Up asana can be performed by anybody.

Pranaprathista which is known as "consecration" is a process which will be followed for invoking the power in the Idols of various Hindu Gods. Generally, this is a three-day process. The entire process is explained in Vedas and with minor changes, all will follow the same.
A Murthi is created by a human being using a stone or a metal. Many of the Hindus believe in worshipping Murthis. As per Hinduism, each God is having a portfolio and he will also have a shape. The people make Murthy as per the shape and size mentioned in Agamasatara. This man-made Murthy will aid them to get success and get their wishes fulfilled. Many of the items made by human beings are useful for enhancing their capability. A human being can't fly but the aeroplanes made by him can be used by him to fly. In the same way, this Murthy will also extend his capabilities in attaining the desired goals.
When these idols are installed they do some Poojas and homes so that the energy will be entering into these idols. The sound waves that are coming from the priests who recite various chanting create energy in the Murthy. The Poojas are to be regularly performed so that the energy will be maintained in the idol. It is like refilling fuel in the vehicle so that there will not be any problem for the movement. That is why in temples people say that pooja should be performed without fail every day. Prana Prathista is to be done with all the rules and regulations suggested in Vedas.

The Prathishta of the worship idols in temples is done following the prescribed ritual regulations and procedures.. There are various procedures and it depends o which procedure and system one follows.
The Shilpi creates the idol following the prescribed observances or penance and practices. Once the carving is over, and the idol ready to be consecrated. It is the procedure to invoke the divine force into the idol. From then on it is not a carved idol but the 'Bimbam' for worship. The divine energy is present in it. The energy y is preserved by the daily rituals and ablutions.
There are long drawn rituals and procedures of many days. There are some very interesting procedures also. The idol immediately on invocation will be having immense energy that no one is allowed to be in front of it. A mirror is kept in front and slowly the wrapper is removed from the eyes of the idol so that the sight falls on the mirror and on its own image. Then further rituals follow to to limit the energy to the optimum level needed to safeguard the worshippers.
The Pratishta idol is fixed to its 'Peetam' or seat by a mixture of various herbal items which are medicinal as ell as fixing items. The daily pooja procedures are also decided based on the deity, the system they follow and the material of the idol. The abhisheka materials(Bathing liquids) are selected in such a way that they do not corrode and damage the idol.

The Prana pratishta is not a small or simple one. It needs persons with great knowledge and experience in this regard. It is believed that if mistake or deliberate error happens, the persons who are doing this will be affected.
Hence it is mostly done with utmost care and under supervision of well experienced and well learned persons in the field.

If we look into the literal meaning of the work 'Pranaprathista', Prana means breath i.e life-giving force and Prathista means consecration which is a live process. When we combine the two words as one, it means we are inviting the deity to enter the material form in the statues and are known as Pratima, Vigraha, or Murti. Vedic rites and mantras are chanted as a ritual invoking God to enter the Statue during the installation in the temple. The Pratima pratishta ritual is a celebration of every devotee in both faith and spirit which has these eight parts as described below:
1. Karmakutir: This is the first part and is often done at the artisan's workshop. Once the Pratima, Vigraha, or Murti is sculpted or made, it is purified by the artisan or a brahmin pundit using darbha grass(A species of grass that is long, stalky, and considered to have purifying properties by Hindus). The artisan or a brahmin pundit touches the entire murti with darbha grass to abolish any evil influences from the murti. The artisan or a brahmin pundit then closes the eyes of the Pratima by daubing a thin layer of ghee and honey over the eyes, perform 200 ahutis or Thomas while chanting the mantras. Before leaving the workshop, a red sacred thread known as Mouli or Kalawa or nada-chhadi is tied to the right wrist of the Prathima or murti.

2. Jaladhivas: Once the Prathima is transported, it is taken to the yagna mandap where the second ritual is to be performed. The Pratima is then immersed in a vessel filled with water, a small amount of panchamrut and other puja substances. The immersing of the Pratima in water is to examine any type of damage to the Pratima as it is believed that the Prathima or murti should be one piece or totally whole without any type of damage. The vessel is then covered with a cloth and the ritual of Agni purification with its mantras are chanted. Once completed, the cloth is removed and the Prathima or murti is awakened by ringing the bells. Once it is complete, the Prathima or murti is completely wiped and taken out of the vessel.

3. Dhanyadhivas: After the Prathima or murti is wiped dry, it is laid in the supine posture on top of grains or pulses usually rice or wheat, and then again the Prathima or murti is completely covered with more grains or pulses as it is considered to further purify the Prathima or murti.

4. Ghrutadhivas: Ghrut means cow's ghee and as cow's ghee is considered to be pure, the Prathima or murti is submerged in it as a way of purification. As ghee can cause slipping and damage the Prathima or murti while handling, it is often altered by placing a piece of cotton wool soaked in ghee on the foot toe of the Prathima or murti. After this, the Prathima or murti is awakened by ringing the bells and then placed on a wooden stand.

5. Snapan or Abhishek: It is the ritual of bathing a Prathima or murti with a liquid and a form of purification using 108 different types of materials. The materials used are panchamrut, milk or water containing the essence of various fragrant flowers and leaves, etc that are poured over the horns of a cow, and sugar cane juice. Each dravya(Sanskrit word that means "substances" or "entities.") is placed in each pot i.e. 108 pots are placed in front of the Prathima or murti in three groups. The South group has eleven pots; the middle group has eighty-six pots while the North group has the remaining eleven pots. The Abhishek or bathing of the Prathima or murti is then performed with the contents of each pot reciting a special mantra as per the content in the pot. This is done as it gives immense power and purity to the Prathima or murti.

6. Netra-anavaran: Netra-anavaran ritual is removing the layer of ghee and honey with a gold needle by the artisan who sculpted the Prathima or murti by holding a mirror in front of the Prathima or murti's face. The mirror is used so that the first immensely powerful vision of the Prathima or murti should not fall on a human being. It is thus offered the murti is offered food that is kept ready before the Netra-anavaran ritual begins.

7. Shodshopchar Puja: After purification and food are given to the Prathima or murti, it is laid on a new mattress with food and a pot of water for one night so that the has a good sleep. While the Prathima or murti is put to sleep, all through the night, ten brahmin pundits continually perform 200 homas and offering ahuti's(offerings made to deities during a ritual fire ceremony) of ghee in all eight directions. One drop of ghee is poured into the pot of water placed in front of the Prathima or murti which is used to sprinkle on the sleeping Prathima or murti to awaken it while chanting uttishtha(Sanskrit word meaning arise/awake) mantras. After awakening the Prathima or murti, it is taken to the inner sanctum of the mandir where it will be placed permanently on the pedestal called pindika. The mason then fixes the murti with cement to the pedestal while the pandits chant the mangalashtak (mantras of auspiciousness). After the cement dries, the brahmin pundits will perform the actual prana pratishta.

8. Prana Pratishtha: The first step in the prana pratishtha is Nyasvidhi which means touching. In this, various deities are invoked in different parts of the murti by chanting Paramatma's bij mantra. The rite starts from the head to its feet of the murti using darbha grass and a golden needle(shalaka). In this, it is believed that breath(prana) enters the murti followed by the soul, and lastly the ten senses that are infused into the Prathima or murti. Once the ritual is complete, the Prathima or murti, the Paramatma resides in it and thus is no longer called Prathima or murti but as diety. Now at the end, a maha-puja is performed and clothes(Shangar) are offered after Abhishek to the diety. Once this is complete, the diety is open to all the devotees.