[jdyer9]

As for how to do it, based on my reading, imagine a mattress on the floor. And then, to follow your comparison, imagine a prayer, particularly an Islamic prayer pose (knees on the floor, hips in the air, head and hands touching the floor). Except as the author describes it, your knees would be up on the mattress, and your head and hands would touch the floor, rendering your torso largely inverted.

Also, I realize that there's a lot more to the Adhan than just this pose, but it's the only easily searchable thing I can think of at the moment.