Wow - this thread has been going since '07!
No - I seldom support the buttstock with anything but my shoulder. Up front I might use a bipod or shooting sticks. More likely to just rest it on my pack, or a rolled up jacket, or believe it or not, just use the shooting sling wrapped snug around my arm. All have worked for me.
Depends on the time & natural rests available. Made a 400 yard shot in Wyoming, using a very handy tree limb, while standing. Worked great. My pard actually snapped a photo of me using the rest. I had just dropped the deer, and was waiting, ready to place another shot if necessary. It wasn't. The deer is just above that line of bright, bright morning sunshine and can't be seen:
For ultimate accuracy, of course nothing beats a good solid rest. I just don't usually find a benchrest in the field. Odd...