Marketpress :: Import with Custom Fields

I have a product list with 530 products (with several unique and different custom fields) and 30 unique stores (that will have access to all products, doing the math, that is over 15,000 products to import)

I would like to use the import via CSV method, but cannot find a way to do this with the current import method.

I would like to be able to create my CSV, run an import and have the site create and populate the custom fields (or run 2 CSV imports, if necessary)

if you are going to provide code, to try, be specific as to what files to modify, where to modify them and steps to perform before and after if necessary