Mo2vation:You can cut them down yourself, but as others have said, you gotta be real careful. DUI provides good instruction. I have a dedicated pair if Scissors for the purpose. Check this out from DUI.
http://www.dui-online.com/newsite/how_to_trim.htm
Be sure to get to your LDS for a class on how to dive these things. You're going to love diving dry once you get dialed in.
K
And . . . If you use scissors make sure they are sharp! I have found a utility knife to work the best (change to a new blade before cutting). Stretch the neck around an AL80, use a small soup can for the wrists. try cutting completely around without lifting the blade and youll end up with a very nice looking seal.