I agree, mapquest.com is your friend... I think it'll recommend Rt 3 N from where you are, that's the route I take and it's pretty direct.
The only thing that may be confusing about mapquest's directions if you enter a "Perimeter Dr" address (that's where the cargo area is located) is that it'll direct you to the other end of Perimeter Dr (South Perimeter Dr, or North, I can't remember)... what you'll want to do once you reach the airport area is just to follow the signs that say "Cargo" and ignore mapquest's directions for that part. It's pretty easy, really.
Nuno