Similar to UsingLaunchd, this is a way to launch a buildslave on a mac without losing DNS resolution.
First, write a script that will start the buildslave - in this example, /opt/buildslave/start. It should be designed to run as root, and to assume the identity of the proper buildslave user.
Then, invoke it as
StartupItemContext? can be invoked anywhere, as root - from an SSH connection, or from an automated process such as cron or cfengine.