The folks who, in my opinion, seem to be the better pitchers don't actively pull the glove in to their chest, but move their body to the mitt. In both cases, the glove ends up in roughly the glove-side shoulder area (with a few exceptions, or course). Looking at the three pitchers at the bottom of this page is a good example. Riveia seems to shorten his glove-side arm and pull it to his chest. Weaver throws his mitt toward home and stretches to reach it. Johnson stretches to the mitt, but it ends up lower, at the level of his ribs rather than his shoulder.
While Rivera is successful with his motion, I wouldn't teach it to a young pitcher. Moving the body to the glove encourages a more aggressive move to the plate and finishing in balance, while Rivera's motion would tend to cause a pitcher to fall off to the glove side of the mound.