Instructions
Turn on your console with the game disc inserted and download the 1.11 patch when prompted. If you have already downloaded the patch, then you will first need to delete it by going into your system memory settings in the PS3 and deleting the file manually. When finished, press the PS button to exit out of the game, then turn off your console.
Start your console with the Jailbreak software enabled and activate the FTP. The FTP will allow you to transfer larger files to your PS3 more quickly.
Connect your PS3 to a server on Filezilla and connect to the same server on your PC. To use Filezilla, you will need to download a client program from the site on both your PC and PS3.
Navigate to the following program directory in Filezilla on your PC: /dev_hdd0/game/BLUS30377/USRDIR/. Filezilla is a hub for downloadable programs and will have many "Modern Warfare 2" patches available within this directory. Select any patches you wish to use (any file ending with mp.ff is compatible) and transfer them to the PS3 where they will patch the "Call of Duty: Modern Warfare 2" game file.
Shut down your console and deactivate your jailbreak software, then restart the system normally. Make sure the "Modern Warfare 2" disc is still inserted in the console.
Create a split screen multiplayer game and the mods you added should now be active. You should see text in the lower right corner indicating if a mod or patch is working.