I've always wondered how they did this.. but i think I got the answer from the comments section.. it doesn't look like his real arm attached to the wall.. it's kind of longer and extended.. maybe a beam or support of some type going through his sleeve and holding him up.. any pics of him coming down from there or how he got up there?

Agree.

agreed. Thats how I think He did it. There was also a guy that floated two feet off the ground in front of the white house, apperently in protest. He had a walking stick to hold him up.

Here's your answer.