Reply to 8 bit gameboy tracks

http://www.therecord.com/news/local/...make-chiptunes

My local newspaper printed this article today about modding a gameboy to make 8bit music. I've searched around online on how to do this but no luck. I have 3 old gameboys, and LOVE the 8bit sound and want to give this a shot. Has anyone heard of this or know how to do it