Re: Hewlett-Packard Scanjet 2400 still isn't recognized by xsane on Ubuntu 7.10 Gutsy. But here's a link with instructions on how to make it work:
http://www.elcot.in/linuxdrivers_download.php
I'm not sure how they can do that, since the SANE website itself says it's not supported: see
http://www.sane-project.org/sane-backends.html