You don't really need this at all but it can be faster if you have map packs n such.

Without the spoofer, you cannot transfer from your official to your jb so spoof your ps3 and transfer over. With the spoof enabled, you cannot transfer back to take the spoof off. Download blackb0x or comgenies file manager to get access to the internal HD of your ps3 (comgenies doesn't work for some people, me included, so you can try it).

blackb0x (for MW2 non bypass):
-Download filezilla to your pc and connect your jb ps3 to the internet (not psn, just be connected to your router so it can get an IP address)
-Open up blackb0x on your ps3 and it will tell you the ip address.
-Open up filezilla on your pc and at the top there are a few boxes. One says host. Type your ps3's IP address in that and hit quick connect.
-greeted with your ps3's internal file system, navigate to dev_hdd0/game/ inside here, your installed games and update are held.
-Go look at your MW2 case on the side at the bottom. It will have the region code (BLUS30377 for example)
-Go into that folder on the file system and inside that will be a "USRDIR" folder. Enter it.
-There will be the patch data you wish to modify. (patch_mp.ff)
-Find a modded patch from the hacks n exploits section here You must login or register to view this content.
-Download it and, if needed, rename it to "patch_mp.ff" no quotations.
-Place it over in your MW2 USRDIR folder and overwrite the official patch (make sure it is a 1.13 patch. 1.11 does not work unless on bypass)
-Close filezilla and blackb0x.
-Transfer back to your official ps3 and sign in.
-Open up MW2 and go to a private match.
-Bam. Challenge lobby.

File manager:
Very similar to the above
-Download a patch you want to mod with and put it on a usb stick. Name it "patch_mp.ff"
-Put the usb in your ps3 and open up comgenies file manager.
-On the left side navigate to dev_usb (there are multiple. Keep trying until you find yours) and find the patch file
-On the right side navigate to dev_hdd0/game/MW2regioncode/USRDIR and your will see patch_mp.ff
-Copy and overwrite your patch from your usb onto your ps3.
-Transfer, MW2, private match, challenge lobby

COD5 has not came out yet. WaW is not COD5. But yes same for WaW and COD4. If you want modded zombie lobbies I would definitely transfer to my CFW first so you won't have to download the map pack .pkg files. If you want to host zombie lobbies, navigate to dev_hdd0/game/WaWRegionCode/language/USRDIR/

Multiplayer
Overwrite patch_mp.ff in dev_hdd0/game/WaWRegionCode/USRDIR/language with the modded one.

Nacht der untoten mods:
More than likely you will want phoenix v4 (check WaW modified patches section) and this comes with default.ff and patch.ff. Put those inside dev_hdd0/game/WaWRegionCode/USRDIR/language and overwrite the original (must be named correctly).

verrukt:
Go to dev_hdd0/game/WaWRegionCode/language/USRDIR/dlcmappack1/language/ and replace the nazi_zombie_asylum_patch.ff if needed. (yes in phoenix v4)

shi No Numa:
dev_hdd0/game/WaWRegionCode/language/USRDIR/dlcmappack2/language/
nazi_zombie_sumpf_patch.f file here
Phoenix 2.3 is the best I think. Alpatch didn't release a v4 for this map.

der reise:
dev_hdd0/game/WaWRegionCode/language/USRDIR/dlcmappack3/language/
nazi_zombie_factory_patch.ff
motionflex v1 in modified patches section is by far the best one

When you transfer back to your official, your maps will not be able to be used. Go to the store and at the top right hit the "view downloads" button. Scroll down until you find your map packs for WaW and MW2. Select download and after it says "activating" it will actually start. This will tell your PS3 that you own the maps. Cancel the download. This activates your maps to be used again. Do this for all your MW2 and WaW maps.

Go on WaW and MW2 to make sure you can use your maps.