Dynamic Shadows in Texture Space Diffusion

Does anyone know of a good way to get dynamic shadow calculations into an irradiance map for texture space diffusion (so I can perform an approximation of subsurface scattering)? I managed to create an irradiance map by having the vertices place themselves into their UV coordinates (see GPU Gems) and rendering it with a second camera.

However, by doing this, I lose dynamic shadows. Is there a better method of doing texture space diffusion that preserves dynamic shadowing? Or a way off adding the shadows back in to the irradiance map?

Are you rendering all other objects in your render-to-texture process? The problem might be, that you only render the skin object, but Unity consequently only renders the skin object into the shadow map.

I implemented this technique myself some time ago and found no other option than applying a custom shader to all other objects, which renders into the shadow map, but is skipped during irradiance map rendering...

Implementing this technique works in Unity, but it's not very efficient unfortunately.