Using Player Sneak (or external hotkey) as a procedure trigger

I'm trying to keep players from having to use their inventories as much as possible and I'd like to be able to switch between different versions of an item using some sort of a hot key. Is there a way to set a hot key as a trigger? I can figure out the rest of the procedure, just need the starting point!

Event logic.

Player has Building_Rock in hand

Player sneaks or presses a non vanilla hotkey

Item in hand converts to Throwing_Rock

Player presses hotkey again

Throwing_Rock converts back to Building_Rock