Because autofs is implemented in kernel-space, your kernel must have support compiled in. In 2.0.xx it is an experimental option, but appears to be quite stable. In 2.1.xx (and presumably 2.2.xx) it is not experimental.
The automount program and its configuration files are also necessary; using the rpms (from RedHat, as part of the install) is a great way to go. The automount program should be started by an rc script under the /etc/rc.d/init.d directory . The rpm installs this, but you will need to make sure it gets started, either by linking it from your rc?.d directory, using Redhat's control-panel, or on another distribution by getting the thing started anyway you care to. Non-rpm distros will have to do whatever's applicable to their system. And don't look too hard at what the rc script does; if you're reading this howto you probably don't want to know.