I think he means the minimap.
If thats the case, heres how to do it.
-Find the maximum x,y co-ordinates of the map. (Easiest done by looking at the DMAP in a hex editor).
-Measure the width and hieght of the minimap (in pixels).
-Divide the first by the sceond for the ratio of pixels/co-ordinates on the minimap.
-Inset mark onto the correct pixel