This material (+models) are free to use any way you like I've spent some time trying to get the right properties for the material so that it not only lets the correct amount of light through, it is also a bit transparent as shown in the picture.
Too bad it does not work in bgengine, its hard to get a tranparent material (not talking about alpha textures)
But good for some shots ;)
Try and bake it to a norm map and see if that works in bge.
I've been looking for something like this! Thanks!