My dad has an HP DeskJet 990C. On his printer, with his drivers, I can select a paper size of "4x6 with tear-off tab," which is precisely what I have to print on (HP Premium photo paper).

In the application, click File then Page Setup. Click Paper Sizes, and then select Manage Custom Sizes. In the Manage Paper Sizes window, click the plus sign (+) to add a new size.

"This driver does not support the banner and custom paper printing supported by the Mac OS 9 printer driver." users cannot print to custom papers sizes in Mac OS X using Epson or Canon printers.