I'm working on a (US) zip code based shipping module for Ecommerce v.6.
First, I added a field named 'ShippingZip' to the OrderForm class. There's a list of 10 zip codes (set in config file similar to Simple Shipping Modifier) that get one rate, and any other zip code gets the default rate.
I thought I was on to something with the populate defaults recipe but still no luck.
If anyone can point me in the right direction on this I'd greatly appreciate it.