Help required!!!

You will have to take permission from ICAI for doing addtional course during articleship.  Your first preference should be completing CA with sound articleship, so dont compromise on either for doing CS.  I think upto CS Inter, it wont be much trouble along with your articleship.

In case you find it difficult to go for cs finals along with ca then better postpone it till clearing ca, although ca students do manage to pass cs along with ca.  Its for you to decide...Howver you will have to go for cs training only after completing ca articleship.