"I'm being considered for a promotion to vice president and will participate in an all-day psychological assessment. How should I prepare?"
The most important thing to do is answer as honestly as possible. Don't try and give answers that you think they want. Rather, filter your responses based on your values and beliefs.
You might consider spending some time reflecting on the top 10 defining moments of your life. This is a simple, but powerful, way to remind yourself why you make the choices that you make in life. If you take this step, your confidence will jump through the roof.
This assessment is just one data point, probably designed to see how you react under pressure and deal with conflict. There will probably be a post-assessment interview. During that discussion, you can offer a deeper understanding of your worldview. The most important thing you can do is know what challenges the organization faces and how your value will help them successfully address these challenges.
One last thought: Vice presidents are responsible for driving better business results. I suggest a future-centric, people-centric and customer-centric framework.
Remember there is only one word that helps with confidence. That word is "preparation." Good luck!