There's a tool called PRET - the Printer Exploitation Toolkit -- "the tool that made dumpster diving obsolete" -- that some of you might find fun and useful. You can use it to test which print protocols (ps, pjl, pcl) the printer uses, and then send files to print directly using one of them. It has a bunch of other interesting functionality too.
https://www.github.com/RUB-NDS/PRET