A few ways, depending on what you need to accomplish.
1) Directly in the Effect Controls you can only keyframe the UV offset.
2) As I recall, if you set two different materials for the two groups in Animation engine, it will interpolate between them.
3) The most flexible approach is to use AE layers as texture maps in Element. This way anything you do in the layers will update in Element.
Kalleheikki Kannisto
Senior Graphic Designer