I've decided to add another reply to this, in case the OP comes back and reads this thread.
If you don't have CUPS installed, get it from the Slack CDs (can't remember which) or from here
and install it with
# installpkg cups-1.1.23-i486-1.tgz,
from within the directory in which it's located. Then, start CUPS with
# /etc/rc.d/rc.cups start.
If you get permission errors, make the file executable with
# chmod a+x /etc/rc.d/rc.cups.
You should then be able to point your browser to http://localhost:631
and click the option "Manage Printers", where you'll be able to add your printer. The various pages you'll see should be pretty self-explanatory.
HP printers are good! I was able to set mine up with CUPS (although it's connected to a Windows machine) and it worked with no problems whatsoever.