Campo nailed it for me as to why I own one and its various uses... I own a bowmender from WWAG, too. I'll definitely have it and an extra string (and probably an extra bow, too...) along with me on my elk hunt this coming August; I can't imagine driving that far and NOT having one.

Here's the press in action:

http://media.putfile.com/Bow-Press-How-To

Don't know how difficult it'll be to get your hands on one, but well worth it if you can.