Combine all of the ingredients in a mixing bowl and whisk until the condensed milk has disolved into the coffee mixture. Refrigerate for 1 or 2 hours and pour mixture into an ice cream maker and freeze according to manufacture's directions. Alternately, pour the mixture into a baking dish and place in the freezer. Every so often scrape the mixture with a fork until frozen but still slushy. Serve immediately or store in the freezer for up to 2 weeks.