a friend gave me a Ardupilot Mega 2.0 board to play around with, he doesn't use it anymore and I was in need for a quadcopter flight controller

Now, I know that there is an "Arducopter" software, but since I'm a fan of the Multiwii firmware I'd really like to flash this one onto the board. Is there any way I can do that? Some (minor) code changes wouldn't be any problem as long as there's anyone here who could tell me what I needed to change in order to get it to work with the APM 2.0...
Thanks!
Malte