Well, it looks like I finally got NBCom to work. It's not actually very hard to install, however, the documentation isn't always as clear as a rabbit might hope.
There's actually a bug in it: If your blog's title has apostrophies, NBCom's generated hdrs.php will be illegal.
One main point that the documentation misses is that the blog must be configured to have permalinks as individual pages (by which I mean, when you click on a permalink you get a page with a single blog entry) to work properly. That's achieved by setting ENTRY_ARCHIVE="1" in your blog.conf
Anyway, you should now be able to comment, so go wild!