Seems to occur when I face away from the wall, hook, and push back during the little hop that occurs when the hook retracts.
Turns out you can do it with a normal jump as well or basically any falling motion. Also, spamming left and right also seems to work in some situations.
Sometimes you can use the hook form of the glitch to go up instead of down, but I THINK that the jump can only go down.
Seems to be pretty useful if you want to complete the game fast or just want to mess around.
