When you configure a CUPS or IPP printer on MacOS X, it sets the queue name to be ipp://servername/ipp/printername
Under linux (Redhat 9), the queue name is ipp://servername/printers/printername
To edit this, on the MacOS X machine you need to
# killall cupsd
edit /etc/cups/printers.conf
#cupsd
Thanks to Elliot Messenger for supplying the MacOS X laptop and letting me attempt to destroy it