Use the Eclipse update manager to install "Subversive SVN Team Provider" from the Helios Update site. Restart your Eclipse. After the restart Eclipse will start the Connector Discovery which allows you to install the connectors. Use SVNKit as a connector if you are behind a proxy.

If this installation does not work you can install the connectors directly via the update manager http://www.polarion.org/projects/subversive/download/eclipse/2.0/update-site/