I want to change the login screen background in Lion, but I can't seem to figure out how. I've followed instructions for changing it, but even after restarting, the changes don't show up. I've also tried Loginox, but that didn't work either. Any suggestions?
The easiest solution is to use "Deeper". You can download the beta version which works with Lion 10.7.4 (assuming your using Lion of course).
You can download it here. (Initiates download)
Deeper is a personalization utility for Mac OS X which allows you to enable and disable the hidden functions of the Finder, Dock, QuickTime, Safari, iTunes, Login window, Spotlight, and many of Apple’s applications...
Example of option to modify login screen:
You can also revert your login screen back to it's default settings if you so choose.
There's also Loginox which does basically the same things as Deeper.
Considering how drastically Apple changed the loginwindow and its various properties, you might also want to leave some feedback requesting that they make it easier to manage (ie, setting a 'property of' type banner message shouldn't require a 3rd-party utility).