I never found a way to assign seperate quantities to attributes, but I did make it work based on absolute's suggestions. Basically I modified the product listing page (I think its tpl_product_listing.php). Once you reach a category that has no more subcategories, only products, this is the page that displays. I then made it so that each of the attributes i wanted to sell were their own product, so I would have a category for a photograph and then each photo would have products like 5x7, 8x10, etc. I had to change the tabular_display under the common folder as well and modify the category_rows file. To check out the finished product go to:

sphotos.biz

Hope this helps