Pinning is done by using the top, "knife edge" of the tip with the acceleration exactly at the ball. It's lethal to "stun," draw, or put "quick english" on the cue ball - it is best suited for slower or worn cloth. This requires a very precise motion with the hand and wrist immediately at cue ball contact.
"Pinning" is similar to a Japanese martial arts punching technique - put your fist 15 degrees in and 30 degrees down and hit with two knuckles, rotating your hand at impact. This uses less mass, however the results are piercing and can do severe damage. Of course with pool you don't rotate your hand, it's done with your wrist/finger release.
Efren does this on a regular basis and you can hear his cue make a high pitched sound. Anyone that doesn't know what he's doing would think his cue might be broken.
This may seem easy to do, however, it's not a beginner/intermediate technique. Road players that I've been around use the TOI and Pinning techniques together. The cue ball contact is more precise, which, in effect, makes the TOI (or TOO) more effective.