Yes its possible to change the platform from the sales and Marketing to the IT field. Its best to prepare for the SAP certification (Sales, Marketing and ABAP) in the Modules you are interested and in the field you are working Sales or Marketing domain.
If you start as fresh in the IT industry, the salary package will be very low if you are opting as a programmer or trainee. Else if you are looking for the IT Enabled services like Call centre its also the same starting as a fresher in the same IT field. Its possible to get more package in the field of understand of IT in sales and Marketing where your education counts, experience counts. Later on its possible to catch the career ladder very easily in the Middle Management of the company in IT field itself.
This takes a short time for the preparation of the certification and also for understanding will be very easy for you since there is three plus experience in the Sales and Marketing. The pay for the SAP employee is more when Compared to a normal IT starter trainee.
Apart from these there are C,C++, VC++ programming in the Windows, Unix, Linux environment.Also if taking Java programmer as a carrier its also important to have experience in the field, else it will be starter package only. Computer Graphics like Maya, Autocad, Adobe products understanding and working requires time for training and understanding and searching for the suitable position through career websites like Freshers world, Monsters, Naukri, Times jobs.
In the field of experience with IT knowledge and SAP certification its possible to look for a job in the IT industry with best package.