This won't help you today, but O'Reilly
is publishing
Perl for System Administration
in July of 2000. According to the O'Reilly site one
of the chapters is going to be on user adminstration.
This will probably not help either, but Cobalt's RaQ systems have a web interfase that allow to create/modify users, ifconfig, httpd.conf, and reboot the box. They use perl (for the GUI at least).
I think they run a different httpd, on port 81, maybe with a different configuration.