Here are pictures of two versions of professionals doing

Eka Pada Rajakapotasana

Here is the full-pose:

http://whereintheworldisjennifersantiago.blogspot.com/2010/06/asana-of-month-king-pigeon.html

Here is a variation of the pose that I was able to work up to:

http://www.christineborgyoga.com/photo/variation-on-eka-pada-rajakapotasana/

And lastly, Here is a photo of me doing the above variation: