Can anyone help?

I'm trying to get my Xerox Docuprint M-750 (USB) working under slackware 9.1

I've had this working under a redhat build so the printer definatly works, however it was a pre-built corporate client and i don't fully understand the setup behind it.

As far as I know all i need is cups install and a ppd file (i've taken this ppd file from the redhat install and copied it over to the slackware machine.

I've then tried adding the printer with the command line..

/usr/sbin/lpadmin -p printer -E -v /dev/usb/lp0 -m /etc/cups/ppd/m750.ppd

and get the message:
lpadmin: add-printer (set device) failed: client-error-not-possible

I don't know how to fix this...
Have I missed a step?

I keep seeing stuff about foomatic, what is it, and is it needed?