On press and hold button?

hey!
id like help with creating a button with the following functionality…
if u click it, it acts like normal… and runs some script or sets a value or whatever… but how do i do it so that if the mouse button is held down while on the button it would after 2 seconds keep runing whatever its told to do untill mouse button is released…

im making a volume controll button, and want it to by 1 click jump up 1 % in volume, but as this gets tedious to press , i want it to go up by 1 really fast if its held down … thanks =)