Theoretically, if you're renting points, the actual DVC member is supposed to be the only one who can make the DME reservation for you. At least that's what Disney has always said.
Reality, however, is much different. DME is not Disney. They are a contracted service to Disney and don't really much care who makes the reservation. Once you know the Disney confirmation number and all members of your party are listed on the reservation, just call DME at 866 599-0951. Give them the confirmation number and your flight info and they'll set it up for you. It's quick and easy with virtually no hold time.
DO NOT call the central reservations number. They will most likely be unable to actually help you as they don't have access to DME's system and can't make an actual reservation. All they can do is fill out a form and forward it to DME.
Also DO NOT call DVC Member Services as they, for sure, can't (won't) help you if you are not a DVC member.
Steve