Things You'll Need
Instructions
Download DSx86, a PC emulator designed for the Nintendo DS (see Resources for a link).
Download 4DOS (see Resources), because DSx86 does not have a built-in command interpreter.
Connect a flash card reader to your computer, and insert the Nintendo DS homebrew cartridge.
Create a directory on the homebrew cartridge, and copy all of the files in the DSx86 folder to it.
Name the directory "/data/dsx86".
Create a folder in the directory you just created within the homebrew cartridge. Name the directory for whatever PC game you wish to play. The completed folder should say "/data/dsx86/GameTitle."
Copy all of the game files to this directory.
Eject the homebrew cartridge from your computer, and insert the homebrew cartridge into your DS.
Turn the DS on, and select DSx86.nds from the menu. The DSx86 emulator will begin running.
Type "cd data/dsx86/[your game directory]/" on the touch screen of your Nintendo DS.
Press "Enter" when you're finished.