SourceForge has improved their CVS infrastructure. Instead of checking out all of pkgsrc-wip from scratch, you could just fix the already checked out tree.
You’ll need to change all the CVS/Root files to point to the new CVS server. I have a fixcvs script to do just that — it is common enough to have servers move on you.
% fixcvs /usr/pkgsrc/wip Root 's/@cvs/@pkgsrc-wip.cvs/'
This way you also keep all your local changes without all the work of applying them onto a newly checked out tree.
The original version (or at least idea) for the script is from Christos Zoulas, many many dozens of moons ago…