i think the proper instruction is "take a deep breath and hold it" which seems to have gotten lost somewhere along the line...holding it would reverse the hyperventilation process

Indeed, the deep breath is supposed to be a slow, controlled breath, similar to what's taught in voice training - not a deep, quick breath. Somebody got their instructions mixed up. :)

I learned that lesson the hard way, and I've had panic attacks before, just not by hyperventilation. I thought I was going crazy on top of panicking. Ended up in the emergency room only to find out that I had taken in too much oxygen. That was an "interesting" evening.

As your carbon dioxide level increases up to a certain (relatively-low) point, so does your relaxation.

Source: Anxiety experiments conducted by Joseph Wolpe, Phd in "The Practice of Behavior Therapy, 4ed"

So yes, holding that breath for as long as you possibly can, and then exhaling as slowly as you possibly can, (and repeating if possible) does work.

Yeah, actually, in order to slow your heart down and control your brain, you exhale as slowly as possible. Take a deep breath in through your nose, and breathe out as slowly as yo possibly can through your mouth. This ain't rocket science.

usually a person is guiding and miming the method of slowing the breathing down while they say "take a deep breath" too. It's not just saying the words