This picture shows the process of wrapping the string, which is very intricate. You tape the handle first for addd friction. Once you have the pattern, you attach it at the end with tape and wrap it in a spiral like you would normally to create a grip.
This shows how it looks with the tape overtop.
If you can notice where it switches, the very middle has the string doubled for extra grip and to make it easier to find the point at which it is perfectly balanced.