I wanted to highlight a couple of posts from eriqjaffe's USBL thread are super helpful if you're looking to do backgrounds (so they're in this thread for future reference.)
First, eriqjaffe explained his process
here:http://www.ootpdevelopments.com/board/showpost.php?p=4359897&postcount=16
Second, silvam explained how to do day/night backgrounds here:
http://www.ootpdevelopments.com/board/showpost.php?p=4361526&postcount=21