It would be better to post this kind of question on the ISBoxer forums, even if there is an ISBoxer forum here. They get more heavily monitored for this kind of thing.

That said. I would create a mapped key with two actions.
Action 1, load the menu
Action 2, unload the menu, put a timer on this action, with a pool size of 1, set the Replace timers option, and the number of seconds you want it to display for.

That way, when you press the first time, it will show, and if not pressed again, the menu will unload after x seconds. If you do press the key again, the existing countdown timer will be replaced by a the new one, effectively starting the countdown again.