How to script a logout while screen is locked? I want to log out a user via a shell script, after a delay. However, there's a few other issues:


User does not have admin and/or root.
Logout must complete even if screen is locked.


Currently, I'm using the shell commands below to log out:

osascript -e 'tell application "System Events" to log out'
osascript -e 'tell application "System Events" to keystroke return'


This works fine if the screen is active, but if the screen is locked, this fails, because it depends on triggering a window, and then firing an Enter keystroke. As a reminder, techniques like killing loginwindow fail because they require root.

I'm not convinced it's possible; any ideas would be much appreciated.
Can you get system events to do Shift-Option-Command-q ?? 
something like... (I don't know the exact syntax)

'tell application "System Events" to keystroke q with command down option down shift down'