99.9% of all MW2 modding requires a Jtag. You cannot host online XP lobbies with a USB or on a retail console. If you dont want to buy a Jtag, then you are out of luck. Yet, There are little mods done with USB, you can find them easily.
Concerning GPD's, it is only possible to hex edit to do things like No-Recoil, but you cannot do binds like you can in Black Ops. The reason for it is that Call of Duty 4 had GPD mods where you could do God Mode and No Clip and so on, so they fixed it in Modern Warfare 2.
With this being said, please do not post a thread asking about USB mods or hosting modded lobbies on a retail console.