Couple chants suggested have been 'you're no MJ' and 'Scottie Pippen'
Haha. A "Scottie Pippen" chant would be great.
I normally think that fans should cheer a returning former player the first time back (in the introductions) to show them that they appreciate what they've done for the team, and then treat them like a normal visiting team player after that.
HOWEVER, if the player happens to lead the team on over multiple years, asking for the world, getting it and then failing to deliver and then blaming the team, announcing his intention to leave the team on an ego-driven one hour special without even telling the owner and just acting like a jerk, THEN all rules of courtesy are out the window and fans can do what they want.