Can i use the transfer cable that comes with my Xbox 360?You can mod your Gamertag.. to have all the buttons and triggers displayed ect.
Other then that.. not much for MW2.
I've modded my gamerscore, and you can do funny stuff with your avatar.. change the colours of the skin and hair ect with the Hex Editor.
To do all the online stuff.. you need to Jtag your xbox. You can't do anything "Cool" with a transfer cable tbh.