Adding any texture at all and then exporting should give decent flatshading.
With my exporter, it glitches up and aborts if I try and put in "Col0" as the empty name (Parent: Shape Child: "ColMesh0" scaled cube). It exports okay if I remove all the collision stuff but textures appear really high contrast. (Going from "Glow FX"-like to black while turning about 90 degrees.)
Mountpoint appears to be the "Center" defined on the shape, usually the middle of the starting cube you get. By selecting a few points, snapping the cursor to them and in Object Mode recentering the object on it, you can change this.