Can someone explain how to do this and what it acomplishes?
Bonus two cents about the leaf springs: a second set may fit no better than what you have now. I advise either to do the upside down leaf trick, like this:
http://www.mustangmods.com/data/9461/spring_middle_r.jpg
or go to a spring shop and get them to commit to working with you on ride height and have them fab a set.