Are you sure cups is running?
you should see "631/tcp open ipp" in the output.
If not, do
chmod +x /etc/rc.d/rc.cups
Acquaint yourself with CUPS. Put this in your web browser:
Neither avahi nor nss-mdns are required for printing in a normal
Slackware install. Everything you need is present, unless your printer's
required firmware just isn't in the kernel.