The Print dialog box displays the name of your default printer. You can change the default printer name by modifying the LPDEST environment variable. You can also change the printer for a specific application by modifying the application's application defaults file.
Edit your HomeDirectory/.Xdefaults file by adding this resource:
If you do not have an .Xdefaults file, create the file in your home directory.
You want to direct all printed help topics of an application named ImageScan to a printer named laser2 rather than to your default printer.
Add this resource to your .Xdefaults file: