We've added some code to the uc_aac module to also change the image based on the attribute that is selected. You can see an example on this test site http://otgpublishing.com/node/82 After you change the attribute the image changes. The images are uploaded the same as always. We use the alternative text field for each image and type the name of the attribute.
Looks great! 
I do see some jumping around, maybe since I don't have all the images loaded? Perhaps you can do the large image replacement before emptying the image div?
Joined: 08/07/2007