Ghostscript does not have a print command per say. GhostScrip is used to process and convert PostScript files to other formats. Most often, it is used as a print filter, which is a shell script that your printing system parses print jobs to before sending them to your printer. RedHat should have a decent print tool configuration program that would allow you to select your printer from a list and go...
But if you wan to fiddle with Ghostscrip yourself (Certainly a fine way to spend an afternoon).. find the ghostscript documentation (should have been included with your download). and look at usage.. That should tell you what options you need to select an output device (for yoru specificy printer) and other options (like resolution, etc.)
Then you could some something like (as root):
cat test.ps | gs -device (device) -q -r 800x600 - - > /dev/lp0
I don't remember all the switches exactly, but in this example, we use -q for quiet (important, otherwise junk will be send to the printer) and we specify - - as the input and output (standard in, standard out).. Cat is used to pipe the PS file to ghostscript. (Some people will say this is a redundant use of cat, but just ignore them for the time being
). And the output is being re-directed to /dev/lp0 (Your first Parallel port, this might need to be adjusted if your printer is somewhere else. Drasticly different steps need to be taken if your trying this for a network printer.. Once you have all this figured out for your printer, you can start creating your very own printfilters (which I think is way cool. I never could stomach the prepackaged ones.)
Please note however, only masochistic maniacs seem to actually do this. Most other people go to www.linuxprinting.org
and follow through the howtos for their system.