Ubercart add to cart form with quantity option per attribute

I need the add to cart form on each product to display separate quantity fields so items of different attributes can be added at the same time. This is for a photography site, so it makes sense for the customer to order 2 6x4 prints and one 10x8.

Right now the add to cart form is something like this:

Here is a mockup of what I want to have:

I have no idea which hooks to use, or if it's even possible to add multiple product variants in one POST. Is anyone familiar enough with the 开发者_开发技巧Ubercart api to tell me how I can go about doing this.

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I found this googling for a solution to the same problem. Unfortunately I couldn't find anything.

So I made a patch and sent it in to an issue with a similar request - http://drupal.org/node/782154#comment-3925090

The patch isn't tested very well yet, but I will be going live with it or a subsequent solution in a couple of weeks.

Hope it helps.