FSX GPS Terrain Map

Some GPSs have a function where they show the terrain map. Also you can see the terrain map in the Map menu from FSX. Can someone enlighten me if there is a way to get your own gauge (GPS) to show the terrain map - or even just the GPS land/hydro map information.

I am trying to create a map view for my Living world program to allow the user to plot the living world Sim Objects Waypoints. I assumed I could use the GPS or some undocumented map functionality.