I'm guessing Mike means "basic" as in it's fundamental to what makes AI-KI-DO aikido and that it serves as a basis which supports the existence of or that which determines the essential structure or function of Aikido. IOW, no ki no Aikido.
Perhaps this video of Shioda might elucidate what Mike means by "adjust your ki instantly..."
Particularly from 0:54 - 1:02, and then again at 1:32, 2:33 - 2:38.
As for how to train this, I think there are generally 2 ways to do so... by "packing" the breath and/or "twisting and winding". I'm not really qualified to discuss this in detail as to what that specifically entails, but that's what I understand it to be...
Maybe a general example might help convey the idea (as I understand it).
If you've ever pumped up a bike tire, it's essentially the same idea. The tire itself is generally soft and rubbery. But as you keep pumping air into the tire, the tire gets harder and harder. So, when we're talking about "fascia", the inner tube
of the tire is basically what we're generalizing
the fascia to mean.
As for how to use it in a technique, it's simply too complicated to detail exactly how, and probably quicker to show/feel it. The other side of it is, if you have "on demand" access to use it, you wouldn't need a "technique" specifically.... as evidenced by the video above.