Want to be able to print to a cups server via port 9100?
Choose the printer queue you wish to use and then, 

Make sure /etc/services has the following line:

jetdirect 9100/tcp laserjet hplj

If you are using xinetd, create the file /etc/xinetd.d/jetdirect with the following contents:

# Allow applications using the AppSocket / JetDirect protocol
# to communicate with CUPS.
service jetdirect
{
socket_type = stream
protocol = tcp
wait = no
user = lp
server = /usr/bin/lp
server_args = -d <CUPS_PRINTER_NAME> -o raw
groups = yes
disable = no
}

Restart your services:
service xinetd restart
service cups restart

Your CUPS_PRINTER_NAME can be found in the /etc/cups/printers.conf or /etc/printcap files.