Many people ask me it.
Import a pic to stage editor is easy but not so intuitive. It allows to create cities, rivers, roads ecc. realistic, but also it's useful to create a stage without DEM with GpxToXmlTool.
Stage editor can import any format and size, but the image must be square. if it's not square, it'll appear out of focus. Anyway stage editor can import a 32 bit file. Then you can import a 'false' square map like this:
Click to 'load map' and select the pic, then set Longitude Min = 0 Latitude Min = 0 and Longitude Max = 1 and click to 'Update map'.
After you have to decrease Lon max value until stage editor route and map route are the same(around) width:
Then you have to increase lon min and lat min values, maintaining the same difference between lon max and lon min, until map and route fit together:
i suggest to screen map when it's fine, thereby to save values.