I didn't want to make that post any longer, so I thought I'd wait until you asked

. She wrote it out on a sheet of paper, so this is taken from it:
For each exercise:
a) Breathe normally
b) Gently contract inner abs. Put hands on pelvis with thumb under back and first fingers digging in near the top of the pelvis so you can feel when the muscle contracts. You should feel the tension from the muscle, but it shouldn't raise the fingers. This takes about 20% effort. If your fingers raise, you're using the outer core muscles too (wrong).
c) Gently contract the pelvic floor muscle (as though you're stopping yourself from peeing). Again, 20% effort.
d) Muscles should be 'on' gently - should be able to hold a conversation.
Now the exercises:
1) Lie on your back. Do steps a) - d). Raise one (straight) leg up at a time, making sure the pelvis doesn't move. Keep the muscles contracted. Repeat 10 times.
2) Lie on your back again, with your feet flat on the floor and knees up. Do steps a) - d). Bridge the buttocks. Now, take one foot off the floor and straighten the leg. Use the muscles to stop the pelvis from dropping on that side. You should feel it in the opposite buttock. If you feel it in the hamstring or your back, you're using the wrong muscles, so stop and try again. Aim: hold each leg 10 seconds, 10 times.
3) Lie on your side, legs straight. Do steps a) - d) (you don't need your hands on your pelvis, that's just to get used to how to turn the correct muscle on). Lift upper leg slightly and extend behind you. You want to feel it in the upper buttock, not hamstring or back. Aim: hold to fatigue (5-20 seconds), 10x each leg.
4) Lie on your side, knees bent. Do steps a) - d). Hold pelvis and rotate upper knee towards ceiling (feet together), lifting as high as possible without rotating pelvis outwards. You might have to lean forwards to keep your balance, but try to keep one butt cheek above the other. Do it slowly, working the upper buttock muscle. Repeat to fatigue, 10x - 30x
That's it.
The whole point of the exercises is to address an imbalance between the different core muscles. So BW, once that imbalance is fixed, I'll probably be able to keep using this muscle whilst doing the more powerful core exercises. I think at the moment, it doesn't get used at all because the other muscles just dominate.