No ticket purchase required. But you will need to ask the member you rent from to add it for you, as you will be unable to call Member Services yourself.
You can work out with the member how you will pay for the plan (it must be paid for when it is added) or if you're going to do something like a conference call so you can be on the line to give your credit card, or use gift card numbers that you convey to the member. (Keep the gift cards, because if you cancel the money will be returned to the gift card).