I made this for my boyfriend for his birthday this past week (I made him a LOT of stuff!)
Basically you need to find the right belt, and everything else is easy. The back of the belt buckle should look like this:http://s94022903.onlinehome.us/misc/z/belt02.jpg
It basically just "hooks" into the belt holes. I got mine at the thrift store, so I'm sure you guys can find some floating around. They aren't really that common, but I've found a few.
Basically all I did was unscrew the back of the controller to open it up and cut the controller plug. I left all the parts inside, and closed it back up. I didn't do this, but I should've probably glued the hole where the plug was as well - so there's no hole!
I used E6000 glue to glue the belt to the controller, let it dry and that's it! Your own retro revival.