Writing to UAV mipmap levels

Hi,

I need to store multiple volume textures into the mip levels of a RWTexture3D. There seems to be no way to do that inside CG shader.

Alternatively, I could store each mip level texture in a separate 3D RenderTexture. However, 3D renderTextures get only a single mip level (please correct me if I'm wrong). The only thing I could think of is to use Texture3D's "SetPixels(Color[] colors, int miplevel)" to put data from all render textures into one mipmapped 3D texture. But there doesn't seem to be any way to get color[] out of a 3D volume RenderTexture.

Any help is much appreciated.