I have used AHK with this for auto loading of Ore in EVE (from ship to can). It'd be fine if you set all your windows in a predefined spot, recorded where you wanted each click to go and mapped that to a button. Technically you could drive the game with it. However for each window to take mouse input it needs to be in the foreground, so you'd lose control of main+others while the alt is being worked on. I think what gets most people is they want a dynamic click so that the position is read from the main screen and written to the alts, it'd be just as much use (and a lot easier) to have predefined click points driven from keybinds. Whether or not that hits the EULA I couldn't say.