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The material tweaker is a combination of the Material Booster and the Material Blender.
It splits up the material into the component channels and allows you to boost them (changing their contribution to the material) as well as changing their colours using blend modes.
All remaining inputs correspond to the controls in the user interface.
Andrew Comb use the Material Tweaker alongside other free db&w Tools in his Advanced Shading Tutorial presented at the San Diego LightWave Users Group.