Decode Lightmap Nodes

I'm building a shader that let's me use the results of a Lightmap Bake in my own "unlit" shader.  Basically I'm building my levels out of pieces, but I want pretty baked lights, so I bake the pieces, then save off the textures and use them in my shader.

Decoding the Lightmap is a ton of nodes, and is somewhat complicated.  It would be great if I had a node that would give me the lightmap light contribution, and spec output based on my texture inputs, diffuse input, and normals.