I guess you havent heard of alterIWnet.. Cracked multiplayers do work some times as is the case with MW2. i guess its up to the user whether he is a pirate or not.
If you have MW2 ON steam and plan on using AIWnet you will inevitably GET a VAC ban IF you use your ORIGINAL mw2 exe file i.e C:\prog files\steam\steamapps\mw2\mw2-mp.exe
any alteration of the steam apps EXE or dll files = INSTA VAC ban, ANYTHING at all. people do as little as changing ONE DLL file and they make a thread on steam forums calling an unfair ban.
Believe me man if you value your legit game NEVER EVER use these exe with your MAIN legit game, experiment with it on a 2nd PC with a fake origin account but NEVER use it with your primary unless you like having a ban.
EDIT: I just want to make it clear that I am not encouraging or discouraging the usage of the above exe, use it on your free will but do be aware of any and all risks that follow, Like I said before the above crack makes BF3 to Origin as MW2 is to Steam ... just saying ... its your money, your account, your loss. If anything happens to your account DO keep in mind that Razor will in no way compensate you and EA origin will not even look twice in your direction.