Quote Originally Posted by DrByte View Post
The entire shipping class infrastructure is based on one aggregated quote, rather than individual item quotes.

If you wish to adapt it, you'll need to rework the shipping class and the shipping-module class (ie: UPS as you suggested) to request and display quotes on a per-line-item basis, pass them back to the cart, and formulate the display as desired.
Then you need to make sure it quotes, retains, and re-displays the same quotation information on the shopping-cart, shipping-estimator, payment, and confirmation pages, which will require rewriting templates for those too.
I've been attempting to compile all of the checkout pages and figure out how the shipping weights are being added > then passed to the UPS module > shipping options are displayed > option price is sent to payment checkout. It's extremely difficult, I know, but given a starting point I can figure something out.