So, I found this hack of MMX3 https://www.romhacking.net/hacks/4104/
that converts the game from PAL to NSTC, problem is that in my PSP it hangs on loading. It never goes anywhere.
I've tested it with no compression, it crashes, black screen.
Tried the SLES ID, black screen.
Atm all I think I can do is a mix of the SLES and fake SLUS Game ID, either that or a pops.
I hope someone can help me with this XD.