I was researching the issue of using PowerPrint for Networks on OS X for a while, and found the answer on allosx.com. Since I looked for so long, I thought I'd post this here. Credit goes to Rob Crestani as shown on the original page. Essentially it boils down to this:
pap://*/[AppleTalk Printer Name]/Printer_AdapterWhere [AppleTalk Printer Name] is the name that appears under the Chooser in OS 9 when the PowerPrint device driver is selected (don't enter the brackets). The crucial part is Printer_Adapter, which selects the PowerPrint device.
Mac OS X Hints
http://hints.macworld.com/article.php?story=20030606144829378