Welcome to LQ!
I have no personal experience with your device, but my suggestion is to download the .rpm from the xerox site and then run 'rpm2tgz Xerox-Phaser_6000_6010-1.0-1.i686.rpm' to create a Slackware package. Then, as root, do 'installpkg Xerox-Phaser_6000_6010-1.0-1.i686.tgz'. Then, still as root, restart CUPS using '/etc/rc.d/rc.cups restart'.
I have looked at the .rpm package and it seems very straight forward.
After restarting CUPS, use a web browser to access the CUPS daemon at http://localhost:631
. Hopefully you will be able to configure the printer.
Good luck with this.