Heya, if you haven't yet made 10 posts with your new PFS character alias, you should be able to edit it under the Messageboard Settings on your My Account.
Ok, I figured it out, you have to go down to the Society characters, and hit edit, while you are in your account. They don't for some reason, show up on Alias. If you go into the Society characters page you end up not being able to change the name.