I know there are lots of exchanger out there which accept indian customer and also btcxindia.com which seems to be local exchanger for india but i don't have any experience with them as i am not from india. If you buy bitcoin than find forex which accept bitcoin deposit or try like deposit fund to neteller via bitcoin, transfer it to skrill or directly use in forex.
I appreciate that you replied but I want to whether it is legal for an Indian to convert inr into some other currency and than trade in forex and thatbto margin trading.