Proximamente se podra cambiar la direccion que pusimos en un primer momento segun comenta Major Nelson en su blog :
Now that you have had a few hours to play with the new dashboard update, some folks have asked some questions about the new Messenger integration. Let me see if I can help clear a couple of things up:
Q: I don’t want to automatically sign in to Live Messenger on my console…how do I turn it off?
A: Sign in to Xbox LIVE, go to the Xbox LIVE blade, then select your gamercard and press A. Go down to ‘Auto Sign-in’ and press A. You can set your preference for Xbox Live and Windows Live Messenger separately here.
Q: The email address assigned to my Xbox LIVE account is different to the email address I use on my PC for Windows LIVE messenger. Is there a way for me to still access my messenger account?
A: Not at this time. We are working on the ability to allow users to change the email address they originally used when signing up for Xbox Live. The feature will be available in an upcoming release.