hi devansh, 

This is a very good option to pursue CS along with B. Com

There is no procedure as such its just that you have to register for foundation program and this exam is conducted every 6 months i.e. in june and december. The syllabus of foundation program is quite similar to that of B. Com so you will not find much difficulty to crack the foundation and the second stage is executive, for this you can definitely join a coaching or you can study at home by yourself,whatever suits you better. 

All the best