You can do this protocol using a neutral, wide, or underhand grip. I like to use a different grip each time to create a different stimulus. The isometric is performed at the bottom position because this is the point of the ROM where most people cheat.
Now it's time to take a closer look at the smallest functional unit of training parameters: the repetition. If you build your repetition quality, you'll reap more gains from your workouts. That's definitely a good thing!
Starting with a weight you can curl 12-15 times, do 8-10 reps on steep side of preacher bench, match those reps on the angled side, then stand and rep out.