The WebApps WG and HTML WG use dvcs.w3.org as Mercurial server for developing tests on, which are then (supposedly, at the moment there is a bug) put live on test.w3.org (and test2.w3.org). I forgot everything the second time I had to do this so here are the settings:
Store the following in ~/.hgrc:
[ui] username = Joe User <joe@user.example> verbose = True [auth] w3c.prefix = https://dvcs.w3.org/hg/ w3c.username = juser w3c.password = iamawesome
Use hg clone rather than hg pull to get the first instance of a repository.
And the rest is relatively easy. Just invoke hg.