I just put together a small perl utility that will convert a CVS repo's entire history into a hg repo, with a changeset granularity. It's very simplistic, not very smart and quite slow, but it got the job done for me (I tried to use tailor, but for some reason it didn't do what I expected). If you want to give it a spin, grab it from here: http://www.mgix.com/cvs2hg.tar.bz2