I have never added a network printer, but if you go to
http://localhost:631 you will find the administration guide, as well as the web-configuration tool.
here's a sample command for adding a network printer:
/usr/sbin/lpadmin -p LaserJet -E -v socket://11.22.33.44 -m laserjet.ppd
they said that this is for a printer with a "jet direct" network interface... whatever that is