jsantini,
You are allowed to take DME from MCO to your WDW resort on check-in day and back to MCO on your check-out day. Most DME guests fly in and out of MCO on those days. However, it doesn't matter how you arrive at the airport on your check-in day (or if you really fly out on your check-out day).
Make roundtrip DME reservations. Tell the CM the approximate time you expect to board a DME motorcoach to CSR. You don't have to give them fake airline flight information.
When you fly to MCO, don't use the yellow tags. Retrieve your luggage and take the Airport Marriott courtesy shuttle to the Airport Marriott.
On your CSR check-in day, take the Airport Marriott courtesy shuttle back to the airport. Go to the DME Welcome Center with your luggage.
So you have free transportation (except for the tips to the courtesy shuttle drivers and the DME driver for luggage assistance)!