Look I know Doc is kind of like Francona in that he doesn't like to change things because he doesn't want to take guys off their rythem but I think there is one way to get the C's going on the road.
Start the following lineup... Garnett, Posey, Perkins, Pierce, and Rondo. Let Ray come off the bench. Right now Ray is a defensive liability and starting Posey allows him to defend Lebron while leaving Pierce with Wally who can't guard him. This would allow Pierce to get going offensively early in the game and get into a groove. It would also allow Pierce to expend less energy on the defensive end thus keeping him fresher on offense late in the game.
Oh and one more. Get Eddie some backup minutes at PG over Sam. Eddie is not going to be afraid to take shots when they are given to him like Rondo is but he will also get his shots within the flow of the offense instead of disrupting the entire offense by being a black hole on offense the way Sam is.