[away3d] Phong and directional light inside of a cube

[savagelook]

If I want to use phong shading (with DirectionalLight3D and
PhongColorMaterial) inside of a cube, do I need to create the cube as
6 planes and face them inward?  I tried doing this with the "scaleX =
-1" trick with a cube to turn the normals inward, but all I get is a
flat color on the inside of my cube, no specular or ambient.  Am I
missing something here or can you not use phong shading on the inside
of an object?