Actually, you can't "rent points." You will be renting a reservation either way.
Surely the easier way to rent is to specify your dates and have the owner make the reservation for you. A pre-booked ressie is almost certainly going to be for specific dates in a peak period...designed to yield the maximum revenue for the owner.
You should go to the DIS Rent/Trade board and read the stickies at the top of the page. They outline the process and the posting rules for the DIS. If you have any questions, come back here and ask.
The two key factors in renting, IMHO, are understanding the process thoroughly and establishing a solid foundation of trust between you and the owner.
You also need to be well aware of the owner's cancellation policies, because canceling a
DVC reservation (and that includes "rescheduling") is nothing like canceling a hotel ressie. There are serious issues with a DVC cancellation.