This is from the back part of Caro's "Book of Poker Tells" (#56 and #57).

Basically, you're doing something similar to the "strong means weak" but with a different purpose (Caro lists this one as a strategy at professional level). You reach for your chips as the opponent bets to gain information. I think running one's usual routine for "I'm getting ready to play" is probably just about right, maybe just adding a little force to it at just the right time (which seems to be right at the point where the bet is getting ready to occur).

If he looks back at his cards, then completes the bet forcefully, he's probably bluffing. If he just follows through or else looks at his cards, then completes the bet smoothly, he's probably got a hand.

So, I guess one situation to try this is when you have a decent but vulnerable hand against a bluffy-type opponent.

I think this one is worth working on, actually, in difficult river situations in particular. I'm usually so wrapped up in thinking about what to do that I have trouble putting on much of an act, but I need to keep reminding myself to try to put this play into effect. Looks to me like it would take some fine-tuning before really getting it down.