I want to create a boot up potential which allows a different upstart/runlevel configurations to load based upon specific key downs at boot (or combos). How do I detect a key down event with an upstart script?

I'm offering a bounty. The deal is you must provide a very simple piece of working code to do this. I will immediately check the code and verify that it works. I'm on 10.04 if that helps.

Alternative methods to achieve the same result are acceptable, i.e., if grub could somehow show entries that would indicate a type of boot, where that boot would cp appropriate files to /etc/init. So, instead of a keydown solution, it would be a boot menu item solution and the way to get grub to copy upstart scripts to /etc/init. If possible.