QUOTE
Is there any way Bonjour/PC can be made to 'see' the scanner
Maybe you could put the scanner right in front of the PC?
Seriously, Ethernet is the way to go with mixed machine networks, in my humble opinion. I bought out Brother MFC specifically with that capability since it didn't like using Airport. But it
is connected to the Airport router with that Ethernet cable and then shared with both Macs. I'm not sure there is an Apple wireless router (or any other brand) made with a USB connection in the manner I'm talking about. USB is pretty much a one-machine-to-the-peripheral(s) network. I don't think it was ever designed to connect anything to multiple computers. And, apparently, even Bonjour won't help, either.
Maybe Parallels would allow you to simply remove the PC? That would certainly cut down the networking hassles!