Looks like you already got answers on the HKN forums.

As far as mouse, it's not likely to be very accurate for targeting. Or at least not accurate enough to be worth the hassle. In order to click things in the world, your toons will both need to have the same views, be at the same distance and facing the same way with very, very little variance. It's possible, but you'd be much better off just fixing your script and using the proper target macros in your game.