Just ask your next provider. I think this is a common thing to want to do? Whenever I have asked for this I have never got the feeling that it is something new or strange. If you are respectful and communicate well you can ask for this. I have never been told no by a provider when requesting this position. It seems like a very vulnerable spot for a lady to be in so some comfort would have to be established first.
Be nice. Use your words. It will probably go ok.