Positioning textures on terrain

I've got various scenes made up of 4 terrains, all the same size. These represent real world locations & are made from heightmap information so now I'd like to texture them with aerial photographs.

The textures vary in quality, with the area of interest at hight res, which then will fade into a tiled texture. Because this represents real world locations I've got Lat/Long positions and have a function to convert those in to X,Z. All this location information is read from XML files for each scene. Is it possible to apply a texture at a set position, so that I can accurately match up images to their correct terrain location?

edit - Has this kind of thing never been done before? I've managed to find similar things to everything else I'm doing, but there seems to be nothing at all relating to this.