Baking Texture from vertexcolor.

Hey everybody!

How can I bake vertexcolor map? I was trying something like this:

rm = renderMap p.material.diffuseMap size:[640,480] \
fileName: "frame_.jpg" \
display: true

where diffuseMap is my VertexColor map, but it only make the green-red default map fo VertexColor.

Really appreciate any help!