First, get the invincibility glitch. Have the hookshot in your hand, then while holding z, roll and bonk into a wall, then mash the hookshot. If done correctly, the camera will be zoomed in on link's back and he will start to pull out the hookshot every few seconds. Starting on the 3rd time he does this, quickly use and release the hookshot on the first frame he holds the hookshot up all the way to get a hookshot jump. Make sure you aren't touching the control stick during the hookshot input, as that will make it not work. If you are underwater or have the gravity glitch active while you perform this hookshot jump, you will go much higher.

Neko also has an explanation on how to get one extra frame concerning crouch-stab distance from a wall.