This thread started with rapjr asking about transportation to "the JW at Ko Olina." I assume that means the J.W. Marriott Ihilani at Ko Kolina, not Marriott's Ko Olina Beach Club.
I'm going to assume that there are good reasons why rapjr does not want to rent a car -- even though my personal preference would be to have a rental car, both for airport transportation and to be able to make excursions away from the hotel.
I think it would be possible to have a great vacation at either Ko Olina resort without a car. There are the resort facilities, beach lagoons, and various restaurants at the Ihilani, the Beach Club, and the golf course (Roy's). For golfers, there's golf. The Paradise Cove Luau (which I found disappointing last time) and Fia Fia Night (which I really enjoyed) at the Beach Club are both in walking distance. There are boat tours and boat charters available at the Ko Olina Marina. In addition to all that, there all sorts of excursions to other parts of Oahu available through the concierge.
I did a quick Google search looking for shuttle services that go from HNL to Ko Olina. There are a bunch of them, but if I were looking for such a service, I would call the concierge to get their recommendation.
Finally, there's a Hertz location at the J.W. Marriott Ihilani at Ko Kolina. If a rental car isn't completely out-of-the-question, but just isn't wanted for the entire stay, then one-way rentals on arrival and departure day would be options. Also, renting a car for a day or two to explore Oahu would be an option.