I am going to make facebook the only way to sign up and login once I modify the home theme.
I don’t know what you mean by ‘buddybar’. All I know of is the adminbar, userbar, and optionsbar. You might be talking about the userbar that shows your own avatar and navigation through profile, friends, activity, etc when logged in, and just a login form when logged out. I got rid of that on my member theme.
It shouldn’t be very hard to add it anywhere, that code snippet should be all you need, unless you want a little more customization. You will also probably need to modify or add to the structure.css file within the plugin.