I think to get Ray involved the best way is to run Wally ragged. Send Ray around double and triple screens/picks on the low posts feeding Ray on the wing with the ability to feed the last picker, shoot a wide open jay or cut to the basket using the last picker again. That's just one example but the answer is to set tons of screens underneath and up top for Ray to run Wally into and then get him the ball, whether it be from inside out or outside in. Screens, screens, screens.
When Wally sits and they bring Boobie Wilson in I think the smartest thing to do is a two man iso on one side having Ray post up the much smaller Wilson.
Besides KG, Ray Allen has the most exploitable match-ups in this series. He's faster and a better athlete than Wally and he's bigger and stronger than Wilson. Doc should take advantage of this with multiple plays thrown Rays way to start the game and then immediately when Wilson enters the game.
If Ray goes off on Wally by running him into people and getting open for the shot, then Cleveland will counter with Wilson to have him fight around, over, and through the screens. Once that happens post up Ray. Cleveland will have to adjust like crazy on the fly.