It occurred to me that Huub wrote in gmane.os.netbsd.general:

[pkgsrc-wip]

> Maybe this is the wrong place to ask, but I'll ask anyway: the manpage 
> of csup says that the necessary files to use are in 
> /usr/local/etc/cvsup.

pkgsrc-wip (just like pkgsrc) uses cvs, not CVSup. CVSup is a completely 
and utterly different beast, although it serves more or less the same 
purpose. It uses a completely different network protocol altogether, and
even though CVSup is really nice from a performance point of view (It's
blazing fast, compared to cvs), I don't think TNF would consider using 
it - last thing I know it's still an i386-only thing, in practice.

Really, _all you need to know_ is on http://pkgsrc-wip.sf.net/. Furthermore,
Section 26.4 of the NetBSD guide gives a crash course on some of the 
things you can do with CVS