Since I am not in front of an Appliance right now, I can't remember if this is supported by the Jailbait's initd (busybox?).
Some /etc/inittab's have a line in it as follows:
# What to do at the "3 finger salute".
ca::ctrlaltdel:/sbin/shutdown -t5 -rf now
It got me thinking... man inittab
From inittab man page...
The process will be executed when init receives a signal from the keyboard handler that a special key combination was pressed on the console keyboard.
The documentation for this function is not complete yet; more documentation can be found in the kbd-x.xx packages (most recent was kbd-0.94 at the time of this writing). Basically you want to map some keyboard combination to the "KeyboardSignal" action. For example, to map Alt-Uparrow for this purpose use the following in your keymaps file:
alt keycode 103 = KeyboardSignal
See the Keyboard-and-Console-HOWTO http://www.linuxdoc.org/HOWTO/Keyboard-and-Console-HOWTO-7.html
kb::kbrequest:/sbin/shutdown -h now
in /etc/inittab, and
control alt keycode 79 = KeyboardSignal
control alt keycode 107 = KeyboardSignal
in their keymap. Now Ctrl-Alt-End will do a system shutdown.
Ok maybe combining the line using the "kbrequest" action and using the info under "Useful keyboard remapping under Linux" http://www.linux-hacker.net/cgi-bin/UltraBoard/UltraBoard.pl?Action=ShowPost&Board=MSNCompanion&Post=178&Idle=0&Sort=0&Order=Descend&Page=0&Session= may allow one of the special keys to do the shutdown.