Add the following to the client .hgrc:
[ui] remotecmd=<path_to_hg>Where <path_to_hg> is the path to the hg executable on the main repo machine.
This was from StackOverflow: cloning-a-mercurial-repository-over-ssh
Now, I'm working very remotely from the main repo (6000 miles) so it is worth using compression. Just add the following to the [ui] section of .hgrc:
ssh = ssh -CYou could also configure ssh to use compression by default (see details in link below).
This page has a good overview of using ssh with mercurial: collaborating-with-other-people