Chris,
You should be able to use the PPD file via CUPS to configure the printer. I downloaded the Win10 exe printer driver software that contains the xrx3330.ppd file. After extraction, I wanted to just upload it here, but that isn't allowed. You can PM me and I could send you a link. If this ppd is what you are already using and CUPS won't change the resolution, let me know. I have multifunction Xerox WorkCentre 6515 that is working through CUPS using just the PPD file.