I dont KNOW if this will work, but maybe you could give it a try...

In MED, dis-connect the faces as if stencil shadows werent an issue.

Then re-calculate the normals for all faces.
(/Edit/Select_All while in triangle mode then /Object/Recalculate_Normals)

Then re-connect the faces using Vertex_Mode and the "Merge" button.

Then save WITHOUT doing another Recalculate normals.
This MIGHT work... Ive never tried it though.


In theory this same process could be achieved in another application
than MED if you use one... Assuming it works at all...

[EDIT] Ahhh crap! Thanks Uhwerk. I still keep thinking the
normals are stores for FACES, not vertices.
I know this is the case, but I have to remember to remember...