Head for the mainland side at 2 Eireann Quay, where Bathurst Street meets the water. From there you cross the Western Gap by the pedestrian tunnel, or on the short ferry.
The airport runs a free shuttle bus from Front and York Streets, across from Union Station. It leaves about every 15 minutes, and the trip takes about 15 minutes. By road the terminal is only 3 km from Union, about 5 minutes in a car.
By limo, we pull in at the mainland pavilion curb, beside the ferry building. The airport allows only a brief stop there to load and unload, as its pick-up and drop-off rules explain.
Taxis wait in a corral to the right of the pavilion, and rideshare cars use the lane by Little Norway Park. For an arrival, the car meets you at the same mainland curb, timed to your landing.
Limo Airport Toronto picks up and drops off on that mainland side, at 2 Eireann Quay, for every Billy Bishop trip.