I think you're talking about the team project portal that gets created in SharePoint by default when you spin up a new TFS team project - is that right? If so then those documents actually don't live in TFS - they live in SharePoint. TFS has a loose integration with SharePoint but it doesn't control any of the document workflows, permissioning, etc. I am not a SharePoint expert so I don't know the step-by-step for this, but I know you can implement document workflows with SharePoint as a key capability of the platform.
Hope that helps,
Co-author of Professional Application Lifecycle Management with Visual Studio 2010