How to detect position of each tile on a grid for pathfinding in isometric game

Hello All

I am making an isometric game in flash and wanting to do pathfinding.
I have all the code ready and working fine, the only thing is that I am not able to move my character to the location where the user clicked on the grid. I want to detect the x,y and z position of my tiles on the grid so that i can pass those values to the mouse event function. I am using classes for everything.

creating the grid,
converting 2d co ordinates to 3d co ordinates and back
drawing the grid using graphics.lineTo() and all
A*Star Algorithm

Any kind of help will be highly helpful.

Do you need more info???

Thanks
Iceheros