By 'without Lync Server' do you mean that you are still using OCS? It's not clear what you are trying to do but the CX600 will only work with Lync so device updates are the least of your problems if you don't have a server available.
If you do have a Lync Server then you can sign-in with USB tethering and still receive device updates, there is no requirement to configure PIN Authentication support for updates.
Jeff Schertz | Microsoft Solutions Architect - Polycom | Lync MVP