FastKeys Forum

Run a program if left mouse button or right button is held(pressed) for 500ms or so.

Nice one... This will open Google if the left mouse button is pressed for 1.2 seconds:

Module: Shortcuts
Key: LButton
Type: Command

KeyWait, LButton, T1.2    ;1.2 sec
If ErrorLevel
  Run, www.google.com
Else
  Send {LButton}

In the script how to use time in millisec

Run a program on mouse pressed