Well, I'm not using AHK, but with Keyclone the method described elsewhere in this thread works like a charm on one machine. I'm running three WOW's on one machine and I bind the del key to "strafe left" on my mage and to "strafe right" on my priest, and my paladin's movement is not bound to that key. Tap the del key and the mage and priest jump about a body length apart while the paladin stays front and center. Hold the key down and they run apart until they run into something. I've also got a driud on a second machine with the del bound to "move forward" so that she moves up just behind the paladin to off tank if need be. The simplicity of setting it up in Keyclone was worth $10 to me.

I don't like calling attention to myself, so I played around with permutations of this in out of the way places. But, you can do some nifty parade ground exercises with this set up. I bind strafe right and left then bind /say macros to my paladin who is out in front. So the the Paladin will say SQUAD! DRESS RIGHT, DRESS! and the rest line up. Then bind another key so that the Paladin says PRESENT ARMS! and the group salutes. Etc.

Like I say, I don't use this in public because it tends to attract A LOT of attention and too many questions.