3ds Max Animation :: Building Controller For Mix Maps?

I'm working on a controller for a face rig, but instead of using morphers I'm using different textures for the mouth depending on the action. I've set these up in nested mix maps (there are 8 different textures in all). For my test I'm using 4 and standard primitives to simplify things a bit.

I initially setup these controls in an attribute holder containing 3 sliders. The main one is a master switch slider. The other two act as the mix map sliders within the texture nest of mix maps. I'd like to create a single control for these though.

I can pseudocode this out pretty easily but applying it is a different story. What is the best course of action? I'm not very familiar with Maxscript although I am planning on looking into it.