Seems there was another Sane.pm in /usr/lib/perl5/site_perl/5.12.3/i486-linux-thread-multi/ directory, that had to be linked to /usr/lib/perl5/site_perl/5.12.3/i586-linux-thread-multi/Sane.pm.
Anyway, I did finally get it working, though there are still some rough edges. I decided against the newer source file, and instead went with a Slackware package (gscan2pdf-1.0.0-i686-1jsc.txz). These packages don't seem to deal with dependencies, which meant it allowed me to install it, but then wouldn't work -- I had to use the error messages to figure out what was missing. It was kind of like being in a time warp -- reminded me of the olden days of "dependency hell". Also, as mentioned previously, I had to link various perl modules to another directory so they could be found.
So, it does run. A couple of questions though:
The help viewer needs something called "Gtk2::Ex::PodViewer". Anyone know what package gives this?
There's an error that says, " Can't locate package Cairo::Context for @Gtk2::Gdk::Cairo::Context::ISA at /usr/lib/perl5/vendor_perl/5.12.3/Gscan2pdf.pm line 36." Anyone know where I can find "Cairo::Context"?