how do I print to a cups server
If you're looking to turn an old iMac into a print server so that you can print from another Mac over the network, there's no need to mess around with cups or Debian.

Just install Mac OS X, then go into System Preferences -> Sharing then turn on Printer sharing. From there you can select which printers to share and which users can access them. 

On your other Macs, you can add these printers in the System Preferences -> Print &amp; Fax pane by clicking the "+". If both computers are on the same network, your Macs should automatically detect the shared printers on your iMac.