Bounding Box

Hi guys!

My isometric tile engine is coming along swimmingly, thanks to everyones help.

One problem I having at the moment is figuring out how to figure out which tile the mouse is over when it is clicked. I was told I need to implement a bounding box around each tile in order to figure this out but I am really struggling to implement such a function.

Can anyone point me in the direction of any tutorials / demos which has something similar? I am using AS3.