I have the same problem with and Epson AP5500. I created a form in Server properties of .5" x 3" for slide labels. This doesn't show up in paper sizes though when the printer is selected. Neither does custom in the list.
----- Chris wrote: -----
IF you right click on your printer, and click properties.
Then at the bottom of the screen click on Printing
Preferences. Click the top tab called "Paper" and "custom"
in the middle of the window. Make your changes in this
window then apply.