I wonder if in your meetings with your clients before labor, you can stress that if they reduce the amount of cervical checks/exams, they can rely on what their bodies tell them during labor rather than on what is "found". You can give them examples of what they naturally do in other situations--sit in a semi-squat to have a bowel movement when they feel that pressure, lean over when they have gas, stretch when they have a cramp, rub their temples when they have a headache.
Penny Simkin says: "Often the woman seems to know what to do, and in seeking comfort, also places herself in a position favorable for reducing the anterior lip. If that does not succeed, time and positions that reduce the pressure on the cervix seem to be the best positions to use. Gravity-neutral or anti-gravity positions, such as hands and knees, kneeling on a ball [sic. I think Penny means kneeling over the ball] or the open knee-chest positions ... may move the fetal head away from the cervix and take some of the pressure off. Sidelying, semi-prone, or standing positions ... redistribute the pressure on the cervix and may reduce the lip." She also suggests "Immersion in a bath of deep water". This info comes from The Labor Progress Handbook by Penny Simkin and Ruth Ancheta. This is a great little book to pick up and have in your birth bag. It's a little pricey but maybe you can get it used on Amazon or off eBay.
Now, what to do if someone is intervening? Perhaps you can say, "Gee, Sally Sue. I was just reading about cervical lips in Penny Simkin's book [or on the Midwifery Today Forums!] and she says blah blah blah" and then w/o missing a beat say to your client, "Mary, would you like to try one of those positions?" or to her husband, "Fred, how about you try helping Mary onto her knees and she can lean over the birth ball?" This way you're educating and empowering your clients, you're (hopefully) reducing interventions, and you're educating the birth attendant as well. Perhaps that's the only way they know to reduce a lip!