I get the same problem using CUPS (browsing localhost:631 with Firefox) than using Mac's Printer Setup Utility : the Foomatic driver doesn't appear on the list.
From the CUPS / Add printer page :
On the third screen shot, it says "Add Printer:Model/Driver for..."
We see on the screen shot that it's supposed to show me the Foomatic/foo2oak driver for the HP LaserJet 1500, but I don't see any Foomatic driver on the list.
Looks like I missed a step in the installation process, and the Foomatic drivers didn't get installed on my Mac ?