Auto-repeat macro or key in Alienware TactX?

I've got an Alienware 17 R3 with TactX utility and macro keys, and I want to set up a macro like I have on my Logitech G15 that automatically simulates rapidly repeating key presses or mouse clicks as long as I'm holding down the button.

Unfortunately I don't see a way to tell TactX to automatically repeat a macro or keypress. Does TactX not support this basic feature?

It would be really disappointing to have to use something like AutoHotKey to replicate functionality that was easy to use on my old Logitech G15 keyboard.