First, you need to make sure that the printer has post script installed. Second, you need to enable the PS. Finally, if the printer has an Apple Serial connection or Appletalk, the Laserwriter software installed in OS 9.0.4 will work.
I have my doubts about PS capabilities in this printer: we use several HP4s, and the only one that works with the Mac is the 4PS. In order to provide good Mac support, we must print to newly installed HP 4050N and HP 4500N printers.
Hope this helps.