This is a modification of Midori's Pocket Sling (which you can find here: http://youtu.be/bnU2oP5iHHA). I love this tie because it's comfortable for the wearer and versitile for the rigger. You can play around with how restrictive you want this tie to be. It's great for floor play so have some fun and experiment!
Also, here are some links in case you need more detailed instruction:
Double Column Ties: http://ifavermont.blogspot.com/2014/01/wrangling-double-column-tie.html
Tying Off: http://ifavermont.blogspot.com/2014/07/tying-column-off-using-excess-rope.html
Overhead Double Column: http://ifavermont.blogspot.com/2014/05/the-spinout-munenawa.html