I'd probably go with something simpler, like the thing attached (with the proper handling of starting/stopping the watchdog in a script launched at the proper runlevels, like the fonts/ss).
But that's still only triggered on usbPlugOut, so that's not very useful IMHO. We can always watch for another event, but I don't think we'd find something really more practical than typing the private command in the search box. Plus we'd have to always use a script to launch/stop the watchdog at the proper runlevels, which we don't really need without this.
(Regarding the event in itself, if the Kindle kernel supports inotify, we could use incron/whip up a simple C inotify watchdog, but that's a bit overkill
).
If you really, really can't stomach using the private command, I'd suggest using the hotkey hack posted a few weeks ago
.