Just one more thing - the closest thing to importing polygon data into MoI currently is to get the polygons into OBJ format, and then use the OBJ to 3DM wireframe converter here:
http://moi3d.com/wiki/Resources#Obj23dmWireframe_converter

That converts all the polygon edges in the OBJ file into line segments in a 3DM file, which can then be loaded into MoI and used as a kind of wireframe reference to snap on to as a construction aid.

- Michael