If you are using any rendering program that can output rendered images with separated light passes as channels, you can use this mixer for all the light passes. You can list all the channels you wan't to exclude. Some defaults already listed.
HandyMixer
Updated: 19 May 2015
Author: LeoLiuos
Compatible Nuke versions: 6.0 or later
Compatibility:
If you are using any rendering program that can output rendered images with separated light passes as channels, you can use this mixer for all the light passes. You can list all the channels you wan't to exclude. Some defaults already listed.
And if you wish to edit any channel with let's say with ColorCorrect, if you do it before this gizmo, you can easily change a lamps color in the scene.