Beer stores near Parc Canada, Montreal downtown
You need to go a bit further out of the downtown core.
2 suggestions :
Marché Des Saveurs @ Jean Talon Market
Les Délires du Terroir On St-Hubert St (6406).
Both might have more or less the same selection; but they are close to one another.
Since I'm not familiar with Marché Atwater (closer to your hotel), I cannot suggest a store there.