Install shipping plugin for CRE Loaded

I have a shipping plugin that right now takes the total weight, and total number of items, and the destination zip code and returns the shipping rate from a shipping provider. I need it installed into CRE loaded (a brew of oscommerce) as a shipping plugin so when the customer checks out it takes the total cart contents weight, total cart contents number (quantity) and the customers zip code, replaces the variables in the plugin with the variables cre loaded provides and adds the shipping cost that is returned to the checkout process. I need this done today.