Didn't work for me on 5.00 M33-6. You might have to upgrade to M33-6 before using this, but this is what I used: (Not sure if I can post links to this stuff, but whatever, in the spoiler tag >.>)
Spoiler: show
edit: When you download this, it goes in the PSP/Game folder, and you just do the update in your PSP menu under Game -> Memory Stick.
edit #2: It seems like if you need to update your custom firmware, logically, you would want to upgrade to the highest version on their website, which is 6.25, but from the little research I did when trying to get mine to work, you just want the latest version of whatever you already have. The higher version numbers are just for people that didn't have a chance to get into CFW early on. If you have 5.00, 5.03, 5.50, it seems like you just want to upgrade those to Prometheus 3, and that should play anything out up until this point in time. I'm not 100% sure I fully understand all the stuff going on in the PSP custom firmware though, so, I would still recommend doing a little research on their forums or in other places to make sure you get the right version and not upgrade to a version that no longer allows certain things you're used to using in your CFW (I think 6.25 might not allow emulators or something? I didn't really look through that too much).
XI Wiki



