My memory from classic Mac OS is that pushing the keyboard soft-power key brought up a system-modal dialog asking if you wanted to shut down, restart, or cancel, a dialog with exactly the same design as: <http://www.christianboyce.com/page25/files/tipofthedayjulyth...>

That would obviously not be compatible with a server, maybe if soft power was just constantly held down starting from boot that dialog wouldn't show up?