It would be for host only but I think what you do is this:
**Required Items: 2 PS3's. (1 v3.50 & 1 v3.41) - PSJailbreak Device**
1. Jailbreak your PS3 on 3.41 Firmware. Open up and run the PS3 FTP Server.
2. Open FileZilla (Or another FTP Application) & Connect to your PS3. (Settings At Bottom)
3. Find the MW2 game files and extract the 'default_mp.self' to somewhere on your PC. (Means Drag it to your Desktop or somewhere).
4. Delete the Modern Warfare 2 Game Files. (The Patch) - Restart the PS3 Without Jailbreaking then install the MW2 Patch again. (Go on the Game)
5. New Patch Installed, Jailbreak again, Connect to the FTP Server again (Once the PS3's FTP is running) and overwrite the 'default_mp.self' in the files with the one you have on your computer. Then put Your Challenge Lobby Patch back over the patch_mp.ff.
You Can Now Use The 11th Prestige Function!

Enjoy. Sorry if this is wrong. I'm not really good with this kind of stuff.
**FileZilla Settings**
File - Site Manager - New Site
Host - The IP on your PS3's FTP Server.
Port - 21
Login Type - Normal
Username - FTPD12345
Password - (LEAVE IT BLANK)