Gamecube controller modification

I'm looking to mod one of my GC controllers to help me get better at short hopping in Brawl/project M. What I think I need is when the button is pressed it triggers and then stops after 5 or less frames, about .3 seconds I think, regardless of whether I'm still holding the button or not. My initial idea is to have a 555 circuit hooked up to a button like z, so the circuit completes, triggering the timer and the timer will start to cycle after ~.3 seconds breaking the circuit thus registering as me letting go of the button, maybe add an external potentiometer to adjusting for characters with longer or shorter jumps.

Am I over thinking this? This is just the first idea I thought up. Basic smash rules ban short hop modded controllers so it must have been a problem at some point. but I have never seen or heard of anyone actually having one so I can't find much documentation on the matter.

thanks for any input anyone has to offer.