Okay,first of all sorry 4 bad english.
What FW?
3.41 or lower,if you have lower you have to update with a usb to 3.41
How to JailBreak?
You need a device compatible with it,theres a lot of dongles as you can find for lower than 50$,for example PS3 Key is for 34€,when you have it,just connect it and turn on your ps3 and as fast as you can press the eject button,now you can install other pkg files with other usb,for modded lobbys you need FTP server,Download link:
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Now download FileZilla to your computer,Link:
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Now start FTP server on ps3 and click START,Now go to FileZilla and follow this :
# On FileZilla, click "File -> Site Manager -> New Site"
# Look at the IP Address on your PS3; this will be the "Host" for FileZilla
# On FileZilla, the port you will use is 21
# The username you will use is FTPD12345
# The password you will use is blank (no password at all)
# At the top of the configuration window on FileZilla, click "Transfer Settings"
# Check the box "Limit number of simultaneous connections'
# Set the value to "1"
# Click connect and you should be connected directly to your PS3's HDD.
Now go to /dev_hdd0/game/BLUS30377/USRDIR/' and look for 'patch_mp.ff' (this is the MW2 patch file)
And replace it.
Now theres 2 options just lose the jailbreak and have modded lobbys on the last fw
You have to update to 3.42 and if your hacks work update to 3.50
The second way is with other ps3,just do the data transfer utility from ps3 with modded patch to ps3 with las update u should have the modded patch on last fw
+ rep plz!