VertexPainting and Shaders?

[Murphy]

Hi,
I'm working on a map involving a cave. The cave is basically one huge StaticMesh cut into more manageable pieces and it has VertexPainting on it, meaning I have a rock-texture for walls and ceilings and a sandy texture for the ground.

What I want though, is a shiny shader for both the sand and the rock, but whenever I try to add a shader to the VertexPaint combiner the editor crashes on me.

Is using a shader for this even possible?