Just bought this super cheap (AUD$88) black and white laser and spent a while going around in circles. FInally worked out that it works just fine with the Xerox P8e driver.

So to install, System > Administration > Printing. Click [New] and work out what port you've put it on (LPT or USB, with modern hardware the name will show up), click [Forward]. Now select Xerox and P8e. You're done!

Works a treat! Nice printer at a very competitive price. Even works just fine via my JetDirect which is nice. It's a bit noisy, but it'll be switched off most of the time anyway.