Enable a small Overview Map that moves/interacts with your main map.
The above map has an overview map control that is created with the default options. Much like a regular map, the map contained by the overview map control defaults to a geographic projection.
The second map has an overview map control that is created with non-default options. In this case, the mapOptions property of the control has been set to use non-default projection related properties, and the layers property has been set to use a layer different from the main map. In addition, any other properties of the overview map control can be set in this way.