Actually the buses will go to the AK before 8:00 because of the Character Breakfast in the AK. From your resort, take the bus to the AK, then just walk over to the AKL bus stop and wait for the bus that goes to the AKL. You may have a bit of a wait though because the buses are not prepared to take people back to the resorts that early. When the bus comes ask the driver if he is going back to the AKL, sometimes they actually go to another resort or park.
Give yourself plenty of travel time if you use the bus system. I would be a the bus stop at Old Key West by 7:00 or 7:15. Or as the other poster indicated take a cab from OKW to the AKL.