Material Map Channel change

I am writing a script to batch edit objects after they have been run through a render to texture process. Specifically, I want to be able to change the Map Channel (index int) for a particular map inside of the material editor. I notice that changing this property does nothing with the listener, and I am having a hard time finding any reference to this property in the maxscript docs. Is is possible to access and change this parameter with maxscript? If so, any tips about how I might do that?
thanks

Thomas