I installed official Lexmark driver and scan packages from lexmark.com, and it recognizes the Pro901 (via USB).
I send print jobs, and the print queue says "held". Look further into attributes (right-click on the word "held"), and I see an error message job-state-reasons, "resources-are-not-ready".
Bus 001 Device 002: ID 043d:0185 Lexmark International, Inc.
Basically, nothing happens.