DVD (the seperate legal entity that operates DVC) does allocate a certain percentage of rooms (villas) to Disney. As such, you can make a cash reservation for the DVC resorts via Disney's Central Reservations Office. Availability may be limited. The various codes that often come out for Disney resorts do/may apply to a reservation at one of the DVC resorts.
You can also check out the Rent/Trade Board and explore that route - it can save you a lot depending on when you are going.