Well youd be better of writing the shader in api but. You coudll map the incandandecent channel with an expression or node network that does this. its not realy basic and id have to think of this and as for now im pretty occupied with another enigma and have a splitting head ache.
go to www.pixho com and look at his networks itll clear up the picture for you. But a word of warning if you do not know how the lambertian law works on amthematical level or dont know vector maths you are pretty much out there foating around.