Well since this is not through STEAM, doesn't this mean you could just download the game without any key? Would you still have to have a key for installation? I remmeber having the game downloaded (before i had a legit copy)on my PC SP worked and MP was installed but it would take me to the steam store page, so maybe?
Could you have two copies of MW2, one with the modified files for the servers, and one that remains to go through steam? so you wouldn't have to change the files when you wanted to play on either servers?
"Holding anger is a poison. It eats you from inside. We think that hating is a weapon that attacks the person who harmed us. But hatred is a curved blade. And the harms we do, we do to ourselves."-Mitch Albom