A couple of things you might want to consider when using it:
*the .tga file needs to be the dimensions+1, i.e. a 256x256 map would require a 257x257 size heightmap
*Your map needs to be using the Loarderon Summer tileset when you import the heightmap, otherwise it will not work. You can ofcourse change it afterwards.
*If the program fails to start because of missing .dll files, you can google the name of the file, download it from one of the sites you find, and then add them to the same folder as the program.