Step 1: You must have Custom Firmware (M33 Firmware)
Step 2: Download the Game/App from the links below
Step 3: Extract the .ZIP file
Step 4: Example if you have the game "DOOM" in the DOOM folder will be a eboot.PBP file... This a like a .exe file for
windows
Step 5: Place the Game Folder on your desktop
Step 6: Put your psp into USB Mode
Step 7: Open your psp by going to My Computer and selecting your PSP
Step 8: ms0://PSP/GAME/DOOM/Eboot.pbp
or ms0://PSP/GAMEXXX/DOOM/eboot.pbp
GameXXX = XXX firmware version
Game5XX = 5.00 M33
Game4XX = 4.01 M33
Game380 = 3.90 M33
Game380 = 3.80 M33
Game371 = 3.71 M33
If the folder are not here you make them
Step 9: Make sure you put it like it is above
Step 10: Exit USB mode, and go to Game & Memory Stick