Like Floofies has, you can use Apple Script to activate the Shutdown Script in the Apple menu.

Funny. If you had Timbuktu (the older version is more prone to this than the newer), it has a bug in it. If you try to SSH/Telnet to Timbuktu's port, it shuts down the machine. I am not sure if this would work for an emulated machine but is did for a G4 on OS8 and OS9 back in 2004.