It would be pretty difficult. The CBA forbids any team with a total salary higher than the tax level to complete a sign and trade transaction, and the C's will be around $73 mil if PP/KG stay. The luxury tax is estimated to be around $71 mil next season and assuming Al's asking price is $14-15 mil a year, the Celtics would have to shed most if not all of that. So Green + Lee/Terry would probably be the most realistic option.
Someone can correct me if I'm wrong though, I'm certainly not an expert when it comes to understanding the CBA.
you could get Big Al for Rajon Rondo. The Jazz could use a quality PG... but the Jazz would have some reservations about it since Rondo is coming off major ACL surgery and is still 6-9 months away from even being able to run.
Beyond that, I see no realistic way to land Big Al.
The Jazz would not even hesitate to make that deal. If the choice is to let Big Al go for nothing or Rondo, they pick the 2nd option every single time.
They aren't going to get anything close to that value anywhere else. With so many teams under the cap next year, Al will have plenty of destinations to choose from, and the Jazz will have no choice but to let him walk.