I have no idea how to get to or perform step 3 "In SheepShaver or Basilisk II, use the LaserWriter 8 driver (or Adobe Postscript), and send the printer output to a file in the folder you created in the previous step. In the output options, choose embed all fonts (except the basic 13) and save in PostScript Level 2 or 3 format. Make sure that the printfile has the extension .ps (which it will have by default). "
If you've installed a LaserWriter 8 or Adobe PostScript printer, then print to it from any application. Ignore the Chooser. Don't even think about the Chooser. The Chooser is absolutely useless for this purpose. Just print from an application.
In the Print dialog, select your LaserWriter 8 or Adobe PostScript printer in the Printer: dropdown list. Then, in the dropdown list next to Destination:, choose File. Click the Save button at the lower right corner of the Print dialog. A dialog will appear where you can select the file. Navigate to the Desktop, then Unix, then the name of the folder on OS X that has the Folder Action Script attached. Then click Save.
But follow the other instructions about fonts, etc.