Many organizations’ data centers already maintain and manage a central set of Windows SharePoint Site servers, and restrict creation and deployment of new sites to this set of servers. Team Foundation Server requires installation of a SharePoint Server on the Team Foundation Server application tier and that new team sites be created on this SharePoint Server. This represents an issue for these organizations and may even hinder the adoption of Team Foundation Server for some.
This technical note describes the steps that you must follow to configure an installation of Team Foundation Server to use a pre-existing SharePoint Server that is not on the Team Foundation Server application-tier computer.
Be aware that the instructions are neither simple nor short and it will require great courage to go through it ... Good Luck :)