Sign into the Zune Software with your account. Plug your Zune in so it is recognized by the software. In the upper right corner of the Zune Software, click Settings. A page will open up. In the upper left, click Device. A page will open up. In the list of choices on the left hand side, click Linking.
That should get you there.
Part of a 3 Zune family (an 80 and two 8's). We love the Zune Pass!