Is your focus on access, order processing, commission and compensation management, or something other?
How you set things up is usually driven by the terms of the agreement, the nature of the rep, and the processes you intend to support. If you are working with an independent rep with few or no systems of their, we typically set them up in Sage as a user and as a sales person in SO.
If they are a larger organization and have their own systems, we set up VI jobs and import sales order for the rep's system. That or set up EDI for order processing if it is a really large organization. If automating the interface, It is often important to synchronize part numbers or set up vendor item number aliases in item maintenance to help with the translation.
How specific are you looking to get?