The software doesn't require an RPM database to be installed. The Linux platforms that we do support (Redhat and SUSE) require that this particular RPM is installed for any java components to work (it's actually a requirement for java). Since the Linux platforms that are currently supported do use RPMs, the installer is coded to check for the existence of this particular RPM (by using the rpm command) for Redhat/SUSE.
Since you're installing on a non-supported platform which doesn't have RPM, the RPM check is failing (because rpm doesn't even exist) and you're getting the warning about the missing RPM.
That warning just means that if this were one of our supported Linux systems, there is a very good chance it won't work.
Thanks for the quick reply. The CM is working quite well for me now.
Just as another anecdote, we have an admin here who managed to get the CM and NSH to work for him on a Slackware box. He tinkered with some libraries manually, but otherwise it works for him.