Trigger depression detection

[archiusPendragon]

Alright, so I've been scouring out all the different abnormal weapons I could get my hands on in the base fallout 3 game, and quite a few from mods and the DLC...

My goal is to create a charging mechanic in a weapon based upon how long the trigger is held down - the longer the trigger his held, the higher damage the projectile gets, to a logarithmic cap - thus allowing the user to click-spam the weapon to fire a barrage of lower-damage projectiles, but hold it to fire one high-powered shot at a slower Rate of Fire (ROF).

Now, another thing I want is the ability to swap weapon projectiles and model (which, may be solved in the same fell swoop as the charging mechanic), in order to do... a few various things (those of you familiar with Nintendo might already be on to what I'm planning to try and emulate... keep it shushed, I want a large reveal :P )

Now, I'm not entirely sure how scripting works for weapons (as, even the Mesmetron uses a fancy projectile script). I thought I'd try my hand by looking at the Flamethrower, but that merely has the Automatic box ticked and doesn't really check for trigger depression.

The swapping weapon and Projectile based on hotkey can be worked around (especially if it's a script I use to determine the projectile strength and such) post charge mechanic.

TL;DR - Detect the player holding down the trigger and charge damage of projectile.

Any guidance is appreciated!