Here are the details surrounding the Bulk Shipping Platform. This will provide an overview of the bulk shipping platform, and the objects/calls used to extend it using Apex and Visualforce.
For the latest FedEx, UPS and/or USPS packages, please obtain them from the AppExchange.
To enable bulk shipping, please install the following package.
(Note: if installing into a sandbox org, change "login.salesforce.com" in the URL to "test.salesforce.com")