I just found out that information for a friend who is leaving the ship in Montreal.
Here is the info I got from a member of the Taxi Association of Montreal.
REFERENCE YOUR MESSAGE DATE 27 MAY, 2002.
The distance between the Old Port of Montreal to Dorval Airport is abour 20
km., it takes between 30 minutes to 1hour plus, depending of the traffic.
Example during the afternoon rush hour, it can easily take up to 1 hour and
20 minutes. As an average it takes only 30 to 45 minutes. It is a flat
rate of 28.00$ (Canadian). As soon as a Cruise Ship is at the pier, there
is always taxis available in front of the main entrance.