[G4] OS X Epson Scanner drivers...

[skygram at canada.com]

There is only a beta driver for most Epson scanners. 
So you have to dig it  up on the developers web page
and it isn't officially linked to the Epson web site
per se. On the Epson site find a link to Developers and
you should come across it quite quickly.

Otherwise go to VersionTracker or the Apple web site.
At Apple go to the OS-X tab and go to the Download
section and look for "Epson Twain 5.75T4". It works
well. I have a 1240U Photo and a 1640U.

I have also paid for the VueScan driver and it is quite
excellent.

Bill