Someone uploaded this clip from the home opener in the 1991-92 season, and Whalen mentions that they're launching the new Safeway Score & win promotion (about 4:30 in):
http://www.youtube.com/watch?v=fWeeRPx4zVg
Unfortunately, it cuts out as he's explaining the prizes, so I don't know if the million dollar prize was around from the beginning, or if it came later. They used to give away a trip to Disneyland during every telecast back then, so the million dollar prize may have come later.
Assuming they launched the contest in all the Western Canadian markets at the same time, there may have actually been one million dollar winner. Alexei Zhamnov scored 5 goals for the Jets on April 1, 1995 (
http://en.wikipedia.org/wiki/List_of...in_an_NHL_game).
All of the other 5 goal games for the western teams happened before Score & Win started. The Oilers had 6 five-goal games between 1981 and 1987 (four from Gretzky). The only five-goal game in Flames history was scored by Nieuwendyk in January 1989. The Jets had 2, one in 1982 and the other in 1995. The Nucks have never had a player score 5 in one game.