Just Copy the Script into the Blender Folder...
next step, look in blender under the Preferences and look wheater the Plugin dir is the "Blender Folder" if not , select this one...
Save user Preferences (STRG+U) and restart Blender...
Now the "MDL Script" must be located at the "export" Function of blender.

cYa Sebastian


Tutorials:
[Blender]Terrain creation ENG/GER
[Blender]Low Poly Tree Modeling
[GIMP]Create a Texture for Terrains
CLICK HERE