Guys, please don't try using some kind of forced breath work to do anything of the sort. It could be very dangerous over time and it's absolutely irrelevant and unnecessary. You have to be able to feel the area with increasing sensitivity first, and it will take time. It will help tremendously if you can have a partner, bodywork specialist, massage therapist, etc. help you by actually touching the border points of the sacrum while you focus your attention on being able to feel that area, and later in being able to affect it in various ways by learning to isolate and flex the various muscles of the region and getting internal feedback on how that flexion affects the sacrum. Over time, and it will take time, you will be able to feel the area without anyone touching, and eventually you may even begin to develop some small ability to alter the muscular tension placed on the sacrum, thereby influencing its configuration every so slightly.
Distracting yourself by incorporating specialty breathing methods before this point in time will be an impediment since movement of the diaphragm and the resultant pressure on the organs below it and on the pelvic floor will provide strong proprioceptive sensations that have nothing at all to do with the mingmen, and will serve to at best, delay and at worst, prevent your being able to feel and control the actual areas you are trying to develop.