No expert here so ...
But I think you want to be squatting to allow the most opening in the hip flexors. A birthing chair or similar position would be helpful.
Flexibility and overall good health are important too. I know that women who are good at yoga have an easier time.
There is also the positioning of the baby to consider. Sometimes the baby is facing the wrong way and the woman gets back labor.
Reading the natural childbirth books should give you some insight on how to minimize the pain.
I actually used a doula who did hypnobirthing with me. It was fabulous! I went 31 hours in active labor on a full dose of pitocin with no pain medication at all, and contractions coming 1 minute apart. The pain was very manageable. However after that point things got crazy and I got a contraction that did not subside! I was begging for someone to cut my head off with the fire ax, so they gave me an epidural. But I had the epi for just 3 hours and then I told them to turn it off (they thought I was crazy). Pushing was great, ripping and tearing not too great, but pushing was not painful.
Erin Pavlina, Intuitive Counselor
Connect with me on: Facebook