Hi Robert,
Go to the SAP Service Marketplace -> software download area.
Support Packages and Patches -> A-Z Index -> P -> PI B2B addon.
Go for the B2B DOCUMENTATION 1.0 component for each SP.
Also, check out the SAP help: SAP NetWeaver Process Integration, business-to-business add-on 1.0 - SAP Library
Kind regards,
Dimitri