We have a climber!

Hell hath no fury greater than a toddler who doesn't get his way. Our little guy has continued his insistence on having someone staying in his room with him all during the night. And I mean *all* during the night! I sit in his bedroom until he falls alseep, and then when he wakes up screaming in the middle of the night because I'm not there, I go back and sit some more. When I try to leave when he's awake, he just gets up and climbs out of crib, to find me!
This is a "sleep separation" technique and it's supposed to help, however, I just don't think it's working. Well, I know it's not working because I have spent many nights and hours just sitting around in his room waiting for sleep, and then trying to escape unnoticed - which sometimes is not so stealth-like and the whole process begins again. Yikes. We need to find a new approach because this is getting old very fast and our whole family is cranky