If you want the trigger to always fire (without hold key), then set hold key to 0 in ini file (or press ESC during hotkey configuration for hold key). then turn on the triggerbot with the trigger key (F8 by default, IIRC).
if you want the trigger to fire when you hold a button (like the mousewheel), then you still have to toggle the triggerbot on with the trigger key (F8 by default, IIRC), but the triggerbot will only engage when you're holding the hold key (Mousewheel by default).