How do I access lightmaps in unlit mode, or from the material editor?

Is there any way I can access the lightmaps built by lightmass? I’d like to use them in an unlit material without any realtime shading but only with baked light. I can do it with external tools like Maya and Mentalray, but it’s a long manual pipeline.
So far this solution worked very well and gave me a lot of performance (200fps unlit vs 60 fps lit mode) while still having a nice shading (don’t care if not realistic at all).

There’s no way to do this out of the box, but you could modify the engine to do so. Lightmaps have a special encoding so they are not straightforward rgb values.