I don't know the answer, but since you've gotten no replies let me at least throw out a couple of ideas.
I use a Perfection 610, and the iscan version is up to 2.25 for my scanner. Isn't version 2.10 for 32-bit only? Have you considered trying the Slackware 32-bit
compatibility libraries?
I've also heard that you can extract the firmware and then run the iscan driver under xsane or scanimage. That should work on a pure 64-bit system. The
Gentoo Wiki has a page that might help if you want to try that.