I agree with pedro and ibeam, the mesh should be the easy part. Even for the mouth, because you can use all the existing artwork as refpic : I mean, you don't have to design that idea.
But the tricky part is the texture IMHO. The right color palette, the right feeling within the eyes. Maybe I said just because I s**k at texturing
By the way, my elder son is a huge fan of that movie. I think that I would be his hero one more time if I start working on such a model. Pretty funny...