No, the best (IMO) way to get there is the boat. What a relaxing, fun and beautiful way to go. We have even done it at night when it was cold... just put on a jacket and went for a ride. It's too far to walk and there are no sidewalks along the way. I'm not sure however that you can do the ticket upgrade at Downtown Disney. You could just go to a park and do it at the window without going in... if think you're strong enough to do that....