Not unless they changed something in 12. In NX11 you could setup a native library, but you could only use it for 2D shapes, not component parts. I started a thread on it awhile back, and voiced my displeasure with the "how to" on it, failing to mention that part. Trying to find it now.
You can start to use unmanaged parts but you cannot save anything using this new workflow. Standard parts will need to be managed to be used with Teamcenter. See the details about NX 12.0.1 here: