You need an Origin account.

Clear your browser's cookies.

Get yourself a proxy server based in India. You'll need the IP address and the port.

If you're using Firefox, click Tools, then Options. Now click on Advanced at the top, then the Network tab, then click the Settings button.

Click on Manual Proxy Configuration and enter the address and port.

Click OK. Click OK.

Now, click this link:

http://store.origin.com/store/eaemea/en_GB/home/ThemeID.850300/ccRef.en_IN

You should see prices in Rupees. It costs 1500 RP for Mass Effect 3. Click on it, add it to your cart.

You'll need either a Visa or Mastercard to pay. Enter your details, pay for it etc.

You're done.

I did this for Battlefield 3 back before it came out and I got it for something like £18.50