This article is from the Miscellaneous Macintosh FAQ, by Elliotte Rusty Harold email@example.com with numerous contributions by others.
On a Macintosh you'll need the LaserWriter Font Utility
available on the high density TidBits disk from System 7 or the
More TidBits disk from the 800K distribution. A more feature-rich
version called simply LaserWriter Utility is available from
If you have a non-Apple printer, you may have more luck with the
similar PSTool from Adobe, available at
These utilities allow you to send files to the printer in such
a way that PostScript commands get interpreted as PostScript rather
than as text to be printed. If you're printing to a PostScript
printer connected to something other than a Macintosh, you'll need
to consult your local system gurus. A simple "lpr filename.ps"
works on my Sparc, but your mileage may vary.