Similar: http://www.dual-boxing.com/threads/47954-Mouse-Button-4-and-5-Cloning-using-AutoHotKey

I haven't found a way to broadcast mouseclicks reliably with AHK. It seems that I have to press multiple times to get a click through. I would post my script if it were any usefull. However it causes more pain that is helpfull. You could do most clicking of the different windows by using macros. Write "/fstack" in wow chat and hit enter. the the see button codes for each button. Once you get the name of the butotn you can make macros e.g.
/click "ButtonNameHereCaseSensitive"


If you MUST get clicks through then I suggest trying Hotkeynet or ISboxer.