This kinda depends on how many objects you want to show on your map. In general it's not really hard - have an object on the map as well and on every tick set its coordinates to, for example, map's left corner + original objects X location/map size ratio. So, say, if your map is 64x64 px that is 100 times smaller you would set the map objects coordinates to map's left corner + OriginalObject.X/100
Same for Y coordinates, of course and you are done.