I was going to post this in a separate thread, but for some reason it wouldn't let me.
Guide: How to make custom textures work after January 20th
So today Treyarch released a new patch. Many think that this patch fixed the texture hacks. It didn't, they just messed around with some stuff. I don't even think their intention was to "fix" texture mods, but they only broke it temporarily.
Anyway, here's how you update your files so you can yet again play CoD:BO with texture mods:
1. Navigate to the "..\Steam\SteamApps\common\call of duty black ops\main" folder.
2. Rename all your modded files like in this example: "iw_01.iwd" => "localized_English_bajs_iw_01.iwd".
3. Profit!
Enjoy