Select your model, or a portion of the model you wish to shapeshift, then select Edit -> Duplicate Object. Make sure to duplicate as many heads as extreme poses, and add a translate offset, so that your models are nicely spaced along one particular axis, instead of piled one ontop of another.

As you can see, the head on the left is the base head, and the two on the left are target(extreme) heads. The eyes in the middle head have been rotated to look away, this will be used to creat a shapeshifter control for looking left or right. On the third head, we have closed the eyelids. The positioning of the eyelids will create a control for blinking.