The org.eclipse.team.core.repository extension point is used to add a repository definition. Here is the markup for the CVS client.
<extension
point="org.eclipse.team.core.repository">
<repository
class="org.eclipse.team.internal.ccvs.core.CVSTeamProvider"
id="org.eclipse.team.cvs.core.cvsprovider">
</repository>
</extension>
This registers your team provider with the team support plug-in and assigns an id that should be used when your provider is associated with a project. The specified class for the repository must extend RepositoryProvider.