danielkenobi,
I am not sure where you can find any doccumentation on the Trigger UI system that I built. kinda figured it out myself. It is very easy though…no scripting or expressions. I used curves and attached them to the camera. The inside locator is Parented to the outer square. The outer squares values are limited in the attribute editor…ex -1 and 1. Then I use blend shapes or bones set-up for facial deformations and use set-driven key to run the controls. it averages out the in-betweens. pretty simple and effective. This is done in Maya and could probably be done elsewhere too.
I hope to shoot out a Tutorial on this on my website. I haven’t come accross one yet.