Tips to get the foot over/on your head?

Today I grabbed my foot over my head for the first time -- yippee!  Now I know it's possible.  Problem is, my boyfriend had to literally manhandle my foot and hand it to me.  I have no idea how to grab the damn thing myself even though I can SEE it's close. How can I stretch this move without hanging from a pole?  I feel like the closest analogue is to sit in the splits and lean backward, but I can barely move past vertical.  I have a little more success backbending in different lunge positions.  I can come close pulling the foot while lying on my stomach, but I need someone else's help to grab it overhead.  I have reasonable back flexibility, but I feel like this move is much more about hip flexibility ... true? Pointers please!  Use a yoga strap on my ankle?  Deeper backbending?  Any specific stretches or positions that helped you with a contortion scorpio?  I would love you guys forever!!