You didn't mention what version of Mac OS X you were running, so assuming that you have Tiger, first download and install the driver from
here. If you have Leopard, my bet is that you already have the driver installed.
This printer has its own built in print server, so assuming it's not being shared from a Windows print server, all you need to do is this (excerpted from the printer manual):
1 Turn the power of the printer ON.
2 Open the Applications folder.
3 Open the Utilities folder.
4 Open the Print Center Icon.
5 Click the Add Printer button.
6 Select LPR Printers using IP.
7 Enter the TCP/IP address of the printer into the LPR Printer's
Address box.
8 If you are not using the default Queue enter the Queue name
you are using.
9 From the Printer Model pull-down list select your model.
10 Click Add and the printer will be available from the Printer List.