Top-Down Gui Cursor?

I'm trying to make a top-down 2D cursor, like the cursor in Zap, but I don't know the best way to do it.
I want the mouse to control the cursor and then make the player target the coords of the cursor. Do I need to extend gameTSCtrl, or a guiTSCtrl, or none of the above? Once I make a new gui how do I get the mouse coords and map them to world coords? Any help would be appreciated.

Thanks.