Ok so i saw people post they didnt know what to do so lets see if this helps anyone.
1. Ok download GPDs MEGAUPLOAD - The leading online storage and file delivery service
2. Use GPD in folder 1 to move it to your desktop.
3. Use Le Fluffie to put the GPD onto your profile (worked better for me) DL http://www.mediafire...i2dzfbf9tq8zzdb or Horizon/Modio
4. Move your profile into Horizon and rehash and resign.
5. Once on your xbox it will say black ops but it will have MW3 pic.
6. Delete your account and recover it.
7. Your done mod your achievements if you want to.
Heres a vid !
I hope this helped you guys
This is asking for a ban, but you could do it on a silver/dummy account and show friends.