If you're having some trouble installing PSPMillionaire on your custom firmware, then this may be the fix that you need. Homebrew developer JaX3RiR managed to find what was causing the game to show up as "corrupted data" on custom firmwares, and created a fix to solve the problem.

As it turns out the original creator of the game, PSPMillionaire, accidentally named the file PIC1.PNG as DATA.PSAR. Now that JaX3RiR finally fixed the problem, custom firmware users will now have no difficulty in enjoying the game.

However, do check out JaX3RiR's caveat, quoted below:

This won't work in Slims due to the fact that this game only runs on 1.5 kernel, although the game only has one folder (not PSPMillionaire and PSPMillionaire% like 1.5 homebrews usually have) this also causes the game not to have a corrupt icon, but also it won't work in 1.5. This might work through eLoader in Slims, but as I don't have a Slim or the time to try it through eLoader in my Fat, I cannot confirm this.