Psychology falls under the stream of humanities or simply you can say it is attached to the Arts Stream and before you take up your admission in UG Level irrespective of the university- foreign or otherwise, you must have gone through this subject at least in class eleven and twelve so has to have grips in the fundamentals of this subject.
There would not be deviation of this pattern and hence your thinking of changing of your stream - B.Com just to get admission in B.Sc in Psychology seems to be impossible.
If you are still in India and are really interested to have your basic knowledge in Psychology, you may contact the authorities of IGNOU so as to get your readmission in the Arts Stream for your two years distance courses of class twelve with the suitable option papers including Psychology. This could be your home study plan for completion of the course in the convenient timing. This course would support you in your real mission to have your B.A in Psychology or B.Sc in Psychology in abroad.
Apart from that you need to clear TOEFL or IELTS reflecting your skills for English Proficiency and should have secured minimum 6.5 scores, so that your application could be entertained for admission.
The following are the best foreign universities where you can make your queries for your admission-
1)University of Oxfords, UK, Duration of course- three years, Fee Structure- Rs 44 lakhs per year.
2) University of Melbourne, Australia, Duration of the course- three years, Fee Structure- Rs 38 lakh per year.
3) University of Queensland, Australia, Duration of course- three year, Fee Structure- Rs 21 lakhs per year.
4) Texas A and M University, USA, Duration of course- four year, Fee - Structure- Rs 30 Lakh per year.
5) York University, Toronto, Canada, Duration of course- four year, Fee- Rs 20 Lakh per year.