Mixing and editing for Rock Band (the game)

I just finished a mixdown and edit for a client for a song he was going to submit for the Rock Band video game system. The information I received in regards to all this seemed straightforward enough but I was wondering if anyone here had been through this before - ie. a succesful submission and acceptance of a song for the system? This is my first time dealing with this. Any pitfalls or special things worth knowing about as it pertains to mixing or creating the various stems needed?
 
Thanks

http://www.rockband.com/rock-band-network

That's OK. It all worked out OK. The project was completed and the stems were approved.  I was just curious if anyone had gone through the process already and had anything specific to say about all this. I've played the Rock Band game on an XBox before so I know what it's all about. But this was the first time in dealing with the other side of the coin. I guess you can download and play songs from this website. Might be something worth looking into for some of you songwriters. These gaming systems have a funny way of driving song/album sales.