You might be interested in experimenting with my patched INN. I have
added access control lists for newsgroups hanging off some user
handling in Berkeley DB. I wrote a Perl module, News::INNAdmin and a
CGI script, NAF, to go along with it.
I'm running it in production, but a few things, especially the
installation, are still flaky. Get in touch if you want to report any
hazzles.