Follow these steps to get LSDj working on your Nintendo DS.
Make sure you have a flash card for your DS.
Donate to LSDJ for full version of LSDJ, or download the demo.
Download a gameboy emulator for the DS.
Lameboy – http://lameboy.nutki.com/
Move the emulator onto the games area of your flash card and create a folder for your gameboy games on your DS. Move the lsdj.gb file into that folder.
Open the emulator from flash navagate to folder where gameboys are, select lsdj and make music.