i'm using an hp psc 2510 which has built in wireless (it is seen as a jetdirect)
from my experience I can setup the printer for wireless to print using the hpoj driver no prob but the the scanner is not seen. so here is what i normally have to do to have everything working.
1. make sure the hpoj has been installed by mandrake
2. download and istall hpijs in accordance with the hp directions
3. run "ptal-init setup" from console as root
4. set up printer in cups using the ptal address from ptal-init setup
5. from command line (as root) run the scanner find line (this is not the same as the standard xsane line of code, I'm at work now and can't look it up but you can find it in the install tutorial from the hpijs site from hp)
p.s.
you must restart cups after running ptal-init setup so that cups will see the new connection.
as long as your printserver has an ip address all of the above should work smoothly