You have to know how to Indy Grab before you try this.
This is best when you do it off a ramp. Go at a pretty fast speed then Pop down like normal. But when you pop try not to level out your board too much. If you do then you can't grab it. At the start when you are learning this trick you will just tap the board but after some practice you can do the full grab. When you finish grabbing let go of the board and extend your feet because your going to land. Good Luck!