an old redhat user new to slack, yeah? hehe
Slackware is a bit different... Closer to BSD architecture.
Just edit every file in /etc/rc.d and add comments (this: #) to service you don't want. It will speed up the system (who need to probe pcmcia without a portable or to try setting up quota on a single user computer?) at boot or shutdown.
I think the service your are searching is in /etc/rc.d/rc.inet2 (look for rpc portmapper)
Also, /etc/inetd.conf contain the list of all daemon starting at boot.. it can be usefull to comment some useless thing. It's very easy to get a box with ZERO open port on slackware.