Things You'll Need
Instructions
Connect your PSP to your computer with the USB cable. Your PSP will automatically go into USB mode. A window will pop up on your computer, and you will see the files and folder on the PSP memory stick.
Download the Game Boy emulator for the PSP from the Resources section.
Right-click the file after it has finished downloading and click "Copy." Go into the PSP memory stick and open the "PSP" folder. Right-click the "GAME" folder and click "Paste" to transfer the emulator to the PSP.
Open the emulator folder that you just copied over and locate the "ROMS" folder. Copy and paste your Game Boy ROMs into this folder. ROMs are legal as long as you purchase the license from the creator of the game. In this case, Nintendo is the creator, so you need to contact it before downloading or using any Game Boy ROMs.
Disconnect the PSP from the computer and browse through the PSP menu. Select the Game Boy emulator from the game section and select the ROM you want to play from the main menu of the emulator.