"but is unsupported and has to be installed manually!"
Right, I have seen that before also with a Epson printer. Did you actually proceeded searching for that driver (you should see a "search" button). In my case I easily found the right driver that way.
EDIT: it looks like you are out of luck. Xerox and Visineer do not provide Linux drivers for this model (Let them know!) while SANE also comes up with "unsupported".
http://sane-project.meier-geinitz.de/lists/sane-backends-cvs.html