Atleast explain instead of slapping a link
Yes it does work with the PS3Key v4, i just tried it now. All you have to do is go to the above link, make sure you have a USA copy of MoH, replace the PARAM.SFO in that thread in the MoH folder, boot up Gaia Manager v1.0, and play. Works a treat, and also you can update the game.
The MoH Airbourne shouldn't have an effect on the main game like that, you only removed the install.pkg, correct?
Original PS3 + Slim PS3 - 3.41OFW - 640/320GB - 3 DualShock 3 Controllers - PS3 Remote - PS3 Keypad - x2 Move Controllers/1 Navigation - Jailbroken - x3 PS3Key v4.0 - Maximus AVR USB.
2 Fat PSP's - PSP1000 - OFW 5.00 - PSP1003 - CFW 5.00 M33-6
Original PS2 - Chipped
2 PS1's - Chipped