Two simple steps are needed to access macmini buildbot, which is connected to altair via VPN service.
In your favourite terminal, do the following:
$ ssh -N -f -L 10022:10.8.0.10:22 email@example.com
$ ssh -p 10022 videolan@localhost
where 10022 is the local port on your machine, 10.8.0.10 is the IP address of macmini, and 22 is the port macmini's sshd listens on.