Chris:

[...] test print I get this error

client-error-not-possible

Sounds very much like one of the infamous "can't happen" errors. This means that something has made the program get into an error case that should be impossible to reach. Nice, huh?

cups 1.1.14 LPRng 3.8.5

This is odd. One or the other, not both. I'd go for the BSD-derived lpr, along with magicfilter or similar, as they're very very simple. LPRng is probably overkill for you. CUPS is nice when it works, but is a very monolithic solution.

I seem to remember Slackware leaving an email about how to set up printing in the root mailbox after installation. Does it still?