You must do that with ease or is there prep time?
I haven't had the time or privacy to give a fullhearted attempt.
I give up too soon because it hurts. Laying down with heals over head.
See this link:
http://www.lpsg.org/gallery/showphoto.php/photo/232597/cat/500/ppuser/233992
I just know it took me quite a long time in an attempt sitting to comfortably ease into position.
After that I'd attempt other positions like the lean against the wall or sitting with arms pushing up the upper back thighs/hips.
When I couldn't reach I got satisfaction by at least rubbing my cockhead on my nipples from being in those positions.
I'd be satisfied with that today because I want to get a pic of me doing it.