Hey,
Usually this is done by using sane. That's the general system used to configure scanners. It's like what CUPS does for printers, SANE does for scanners.
I did a search on their site and here are the results:
http://www.sane-project.org/cgi-bin/driver.pl?manu=Lexmark&model=&bus=any&v=&p=As you can see the 3350 is not being returned. So either this device is quite recent and not yet in the list, or it is unsupported.
Regards,
Ben
ps. You could try searching a bit more with google and see if other got it working with a driver for some other device. Although I'm very sure if that method also works for scanners (I've tried it with printers and there it does work).