We selected the car we wanted, gave them the information required. No credit card was necessary at the time of the reservation. We rented a convertible with Dollar using this company. Worked out well. As for insurance check with your company to see if you are covered. Between our credit card and local insurance coverage we did not have to purchase extra.
As Divetex commented they will provide transportation to and from the courthouse, a short walk from the pier.
__________________ Ready to Steer towards another cruise
Most of the major car rental companies have outposts all over the islands. You can do a google search on car rental companies in your port cities, too. Just be really sure of how far their place is from the pier or if they have shuttles.
Book now. When we were in Lahaina for two days, everyone ran out of cars so we swapped with Jennifer and Jose. The car rental people didn't have a chance against such cleverness.
Did you see the story, "Hawaii On Your Own" on the Home Page?