How to make the minimap prieview another type then the map?

How to make the minimap prieview another type then the map?

If you have seen the series Cult of the Damned or Creatures of the Night you will notice that they do NOT have the normal map terrain displayed. Like Cult of the Damned have a image where it says Cult of the Damned Part 1. I know I need a tga. or blp. and thats no problem for me but... after I've imported it where do I make so that it displays like Cult of the Damned??


Plzzzzzz help me!

the tga must have a resolution of 256x256 or 128x128.
import it with the WE Import Manager and change the path to war3mapPreview.tga.