Ok bro keep ur hair on, There is a default_mp.self but you cannot see it because you have no got the latest game update installed!
Solution:
Load mw2 and install update 1.14, When updated dont update to latest OFW
Or:
Search NGU for a MW2 1.14 pkg file then install it thru jailbreak
Or:
Mod another game!
If this helped, Like this Post ?
Regards Subaru.