Slapping has become a great offensive weapon especially for the very fast left-handed batter. Like everything else, this skill should be practiced before using it in a fastpitch game.
The first step is to bringing the front foot back close to and slightly behind the back foot. This opens up the whole batters box to move toward the ball aggressively. The back foot then crosses over the front foot and toward the pitcher. Just think of this as a karaoke step toward the pitcher. It is important to focus this step toward the pitcher. If your focus is on turning toward first base to fast, you will pull yourself to far away from the ball to get the bat on it. The barrel of the bat should be shortened by letting the bat slid down through your hands 3 or 4 inches. This makes it easier to bring the barrel around. Think of it as choking up on the bat.
Jessica Mendoza talks about how to slap.
Two points that I want to make. This is not a bunt, therefore if you hit a foul ball on a two strike pitch and it is just a foul ball, not a strike out. Point two is that this style of hitting does not have to be an infield hit. Have some faith in what you can do it for power