How do I register RHEL 7.2 machines to Spacewalk ( RedHat Sattelite 5 )?

I want to manage RHEL 7.2 machines via Spacewalk which is on RHEL 6.6 until we move to the new Satellite 6.1.8. How can I register the machines to the current Spacewalk and subscribe to a new RHEL 7 base channel for the updates? Any suggestions or detailed steps are appreciated.