Sadly I didn't bind it to a key, as I knw my cycle times so I just set it to wait 60s...

Code:
WinWait, EVE, 
IfWinNotActive, EVE, , WinActivate, EVE, 
WinWaitActive, EVE, 
Loop 30
{
SendEvent {Click 80, 908, down}{click 86, 729, up}
Sleep 60000
}
This was a while back so some parts of that may no longer be current I have no idea.

As for grid idea, you could but I think all you really need is 1 set where everyone clicks roughly 10 yards in front (gather mode); 1 where everyone clicks on themselves (AoE mode); and 1 where you click all around you. Which you use would depend on where the mobs are... If you're really clever you could even add approximate points onto the screen where things will land so you can see whats happening... (Using LUA and eePanels2)