Are you asking if someone who hasn't flown into MCO but is meeting others there (who have flown in) can still use DME? I would imagine you could. But, you have to be staying at a WDW resort (which I'm assuming you are), and you would have to make a DME reservation. When they ask for flight info, I would just give them the same flight info as the others who are flying in have. Then, just go to the check-in desk with everyone else. But, I'm not absolutely certain...if you can't I'm sure someone will correct me.