Nothing out of the box, no. But there could be ways to make this work. With clouds, much of the shading comes from self shadowing, so if you want to relight the clouds in a game engine you probably need normals that somehow allow this effect to be recreated. Without knowing what your exact requirements are, I don't know if this is really what you want, but I would try rendering a normal pass using red, green and blue lights (coming from appropriate directions), and allow them to cast shadows in the clouds to produce shading. The resulting image might work as a normal map. If you use soft shadows with a large soft shadow diameter (maybe 90 degrees?) maybe you could get something that produces reasonable cloud relighting.
Matt
