Samsung Galaxy S II Skyrocket

Now, I may be wrong here because there may be a way to download and have Google maps on your phone to have the navigator pull from, but I don't think you can do what you're asking. When you use the maps, it's locating you by gps, but I believe that is a network thing meaning you'd need to have cell service in order for the phone to know where you are.
Again, I could be wrong with this, but the gps is one thing, and in order for it to know where you are and place you on a map is a different thing. You'd need cell service.