I'm not sure if this has been done before, or if anyone already knows about this, but I havn't seen anyone do this before.
Here's a screenshot of an argonian with larger arms, wider body and chest, and a smaller head.
http://i647.photobucket.com/albums/uu195/mark507_album/screenies/MGEScreenshot22.jpg
http://i647.photobucket.com/albums/uu195/mark507_album/screenies/MGEScreenshot21-1.jpg
You should be able to see the scaling effect in the screenshot. However the effect is quite subtle with that argonian, so if you want I can whip up a more drastically scaled one.. As you can see the armor scaled correctly.
I'm using no new body parts at all.
What I've done is imported base_animKnA into max, and added scale animations to different parts of it. Then I attached the animations to an argonian and there's the results.
I haven't tested the method fully yet, though it seems to work fine with that example.
edit: The possible effects are limited, but it's interesting none the less.