Asante used to make a Mac serial to Ethernet device,
AsanteTalk. If they're still available that may be
an alternative. They used to sell for $99.00. I
used one with an HP-4MP printer (which my daughter
and son-in-law are still using.)
I think you may try what you are doing but do not use
IPP printing because you have the printer connected
to a USB port not an Ethernet port.
Thanks for the info.
Another question.... if I hook the printer up through the Ethernet port can I still run DSL through it?
Also the printer browser forces me to choose either IPP, LPD or HP Jet Direct-Socket.