Mac OS X 10.5 (Leopard)
* Open System Preferences
* Open Print & Fax
* Click the + button below the list of installed printers
* Select the toolbar button called 'IP'
* Set protocol to: HP Jetdirect - Socket
* Enter the address of your router followed by : and the port - ie. normally 192.168.1.1:9100
* Leave 'Queue' blank
* Set a friendly name for your printer (whatever you like)
* And a friendly location (again, up to you)
* Print Using: choose 'Select a driver to use' (On OS X 10.6, choose 'Select Printer Software')
* A list will pop up of all installed printer drivers - choose the one that works for you (see Note below)
* Add your printer
Note (Mac only): the driver must be compatible with the CUPS printing system, which is one of the two printing systems included in OS X. Certain printers e.g. Canon Pixma series and Epson Inkjet include OSX drivers which do not use CUPS. You may find compatible printer drivers from Gutenprint (free) or PrintFab ($). OS X Leopard appears to include certain Gutenprint drivers, but the quality may vary and it may be worth checking their website for updated versions, or try PrintFab.
i got my cannon pixma mp500 printer working with these instruction above using the gutenprint drivers (gutenprint-5.2.8-pre1.dmg) then i chose the CUPS GUTENPRINT CANNON MP 500 DRIVERS