I am trying to set up a store with drupal ecommerce. I have the products working more or less as I want. Now, I need to ship them. If I want to add something that collects rate information from UPS (or fedex or dhl...) would I just hack the shipping module? I don't see the kinds of hooks in the shipping module, that allowed me to write a separate module for products.

Some hacking is required in any case, I think, because the proposed module needs to collect the weight of products, and the shipping address. I suppose that, even if the resulting code were in a separate module, the current shipping module does not hand off that information.

Any advice?

btw, the product module stores the weight and volume of products, and offers 3 price breaks based on quantity. It required some minor hacking of the shopping cart module (or the node module?) to get the prices to work, but it is mostly a separate module. Does anybody want to clean up my buggy, rushed code for public consumption? ;-)