I want to purchase DLC for my RGHed 360...!? please Help

I have a modded 360 and I actually want to purchase some DLC to support the company that is make Rocksmith DLC (UBI SF).... Also I can't find the files on the net anywhere. Problem is I don't feel like figuring out how to use a VPN. I RGHed it to play custom songs on the game.

The problem I'm having is if I log in to live I will get banned before having time to make the purchase.

Question (TLDR):


Is there any way to use my friends retail 360 (sign in under my live account,)...

I want to purchase DLC for my RGHed 360...!? please Help