So now I'm following Lee Joramo's instructions for installing Snow Leopard on the Mac Mini, in target mode. So far I've got the Mini showing up as an external hard drive on the MacBook.
Update: It worked. I got a clean installation of Snow Leopard on the Mac Mini, using the method outlined by Lee. Unfortunately it didn't get the scanner working. I give up on that. I'll try getting another scanner. Canon LiDE 700F is a bad deal. I hear the hardware works, but the drivers are a nightmare. I concur with the drivers part, never got to use the hardware.
http://bit.ly/b8xWMF