ah…you make me tired to find references… however it took a single query to find it on ATI and a few minutes to actually read the quote. It is under method 1. Sounds like chakra meditation to me. This is one of the early books that Ajahn Thanissaro wrote/translated when ATI was the only (free) game in town. aka the 90’s
Then slowly bring your attention inward, focusing it on the various aspects of the breath — the important aspects that can give rise to intuitive powers of various kinds: clairvoyance, clairaudience, the ability to know the minds of others, the ability to remember previous lives, the ability to know where different people and animals are reborn after death, and knowledge of the various elements or potentials that are connected with, and can be of use to, the body. These elements come from the bases of the breath. The First Base: Center the mind on the tip of the nose and then slowly move it to the middle of the forehead, The Second Base. Keep your awareness broad. Let the mind rest for a moment at the forehead and then bring it back to the nose. Keep moving it back and forth between the nose and the forehead — like a person climbing up and down a mountain — seven times. Then let it settle at the forehead. Don’t let it go back to the nose.
From here, let it move to The Third Base, the middle of the top of the head, and let it settle there for a moment. Keep your awareness broad. Inhale the breath at that spot, let it spread throughout the head for a moment, and then return the mind to the middle of the forehead. Move the mind back and forth between the forehead and the top of the head seven times, finally letting it rest on the top of the head.
Then bring it into The Fourth Base, the middle of the brain. Let it be still for a moment and then bring it back out to the top of the head. Keep moving it back and forth between these two spots, finally letting it settle in the middle of the brain. Keep your awareness broad. Let the refined breath in the brain spread to the lower parts of the body.
When you reach this point you may find that the breath starts giving rise to various signs (nimitta), such as seeing or feeling hot, cold, or tingling sensations in the head. You may see a pale, murky vapor or your own skull. Even so, don’t let yourself be affected by whatever appears. If you don’t want the nimitta to appear, breathe deep and long, down into the heart, and it will immediately go away.
When you see that a nimitta has appeared, mindfully focus your awareness on it — but be sure to focus on only one at a time, choosing whichever one is most comfortable. Once you’ve got hold of it, expand it so that it’s as large as your head. The bright white nimitta is useful to the body and mind: It’s a pure breath that can cleanse the blood in the body, reducing or eliminating feelings of physical pain.
When you have this white light as large as the head, bring it down to The Fifth Base, the center of the chest. Once it’s firmly settled, let it spread out to fill the chest. Make this breath as white and as bright as possible, and then let both the breath and the light spread throughout the body, out to every pore, until different parts of the body appear on their own as pictures. If you don’t want the pictures, take two or three long breaths and they’ll disappear. Keep your awareness still and expansive. Don’t let it latch onto or be affected by any nimitta that may happen to pass into the brightness of the breath. Keep careful watch over the mind. Keep it one. Keep it intent on a single preoccupation, the refined breath, letting this refined breath suffuse the entire body.
When you’ve reached this point, knowledge will gradually begin to unfold. The body will be light, like fluff. The mind will be rested and refreshed — supple, solitary, and self-contained. There will be an extreme sense of physical pleasure and mental ease.
If you want to acquire knowledge and skill, practice these steps until you’re adept at entering, leaving, and staying in place. When you’ve mastered them, you’ll be able to give rise to the nimitta of the breath — the brilliantly white ball or lump of light — whenever you want. When you want knowledge, simply make the mind still and let go of all preoccupations, leaving just the brightness and emptiness. Think one or two times of whatever you want to know — of things inside or outside, concerning yourself or others — and the knowledge will arise or a mental picture will appear. To become thoroughly expert you should, if possible, study directly with someone who has practiced and is skilled in these matters, because knowledge of this sort can come only from the practice of centering the mind.