I’m not that experienced, but I have read up on the “Sweet Rewards.” thread, this one and at the evil doctor’s website. Remember that the contraction must be focused just behind the anus, or in front of the tailbone. Anatomically it may not be possible to do this without contracting the entire pelvic floor musculature, including the the PC muscle. As you’ve no doubt noticed in reading this thread, the PC muscle needs to stay relaxed. The evil doctor advocates using an expansion of the lower abdomen and perineum with the breath (a belly breath) combined with contraction of the anus and glutes. This allows the PC muscle to be expanded or relaxed relative to the muscles behind the anus.
In Yoga this is called Ashwini mudra. Various body postures facilitate simultaneous relaxation of the PC with contraction of muscles further back. Stand with your heels together, toes pointing out and hands on your belly (just below your navel). Inhale, feeling your lower abdomen swell and simultaneously squeeze your ass. You’ll find that you can, in this position, easily contract your glutes, anus and pelvic floor while the pc muscle remains relaxed and expanded.
Conversely, if you turn your toes in so you’re pigeon toed, bend forward at the waist and then squeeze your pelvic floor, you’ll find that only the “front” of the pelvic floor, including the pc, contract, while the anus and glutes do not.
So, to learn “anal breathing” is as simple as putting your legs in good position, standing, lying or sitting, and contracting your ass while inhaling into your belly. You can imagine that the contraction is drawing the air or “energy” into the tailbone and up the spine. Eventually, multiple sources contend, actual contraction of the muscles is unnecessary, and one can simple inhale up the spine with the mind.
I hope this helps. Remember that balooning was discovered as a side benefit by someone who was trying to avoid premature ejaculation and last longer. As many of us have found, squeezing the PC muscle is a shortcut to shooting.