By consistently answering questions and contributing to the growth of the category and the wikianswers community.
First concentrate on one category and gain the trust of senior members of the community. Once senior members are satisfied with your contributions, they would offer you the supervisor option for any category that you are an expert in. This way you can become a category super.
Remember: Becoming a super is no joke. It comes with a lot of responsibilities and you will become one among the hundreds of dedicated wikianswers community members who strive to keep the website in top shape.