trouble adding HP PSC-2510 hplip printer to cups

I'm trying to print to an HP PSC-2510 over a network.

It was working under debian sid with hplip 0.9.11-2 and cups (1.2.1-3) .

I have hplip 0.9.7-4ubuntu1 installed in this ubuntu dapper setup; I can get this to work:

$ hp-makeuri 192.168.1.103
CUPS URI: hp:/net/psc_2500_series?ip=192.168.1.103

but I can't figure out how to give that URI to cups. The gnome add-printer dialog adds an ipp: to the front of the URI. The web-based interface doesn't show a URI field.

Also, I don't know what username/password to use thru the web interface to cups; I set a superuser (root) password, but I can't get it to work.

I'm getting all sorts of strange errors from the cups web interface.
"Error: Bad Request" on the printers page (http://127.0.0.1:631/printers/ ). The error log has lots of stuff, including:

E [15/Aug/2006:11:10:11 -0500] Bad request line "DEBUG: Got device list!" from localhost!
E [15/Aug/2006:11:10:22 -0500] Bad URI "http=0x80762a8" in request!
E [15/Aug/2006:11:32:34 -0500] Bad request line "DEBUG: show_all_printers(http=0x8089860, user="guest")" from localhost!
E [15/Aug/2006:11:33:05 -0500] Bad URI "http=0x80762a8" in request!