Bring a pot of water to a boil and immerse the peaches in the water for 1 to 2 minutes, until the skins come off easily. Remove them with a slotted spoon and place them in a bowl of cold water to stop the cooking. Peel the peaches and then slice them in wedges off the pit and into a bowl. Stir in the sugar, Sauternes, and orange liqueur. Cover and refrigerate for at least 2 hours, or overnight. Serve cool but not cold.