Can the Celtics and Pierce agree to change the guarantee date on his contract?

[LooseCannon]

While the CBA does not let Paul Pierce renegotiate his contract to change the dollar amounts, as I understand it, a player is able to agree to change the guaranteed portion of the contract.  For example, Hedo Turkoglu agreed to make the final year of his contract partially guaranteed to facilitate his trade back to Orlando.

While I would expect the league to not allow the Celtics to increase Pierce's guarantee so that they can waive him and re-sign him for the minimum at an effective higher salary, since that seems like a blatant attempt to circumvent the salary cap, I wonder if the CBA permits Pierce to agree to change the date on when his contract becomes fully guaranteed if it would give Ainge more time to try and make a deal.  I feel as if there is a precedent for doing this, but I am drawing a blank.  Does anyone remember a similar case?

[Lucky17]

Vince Carter and the Suns mutually agreed to postpone the deadline by which his contract became guaranteed in Summer 2011:

http://www.nba.com/2011/news/06/23/suns-moves.ap/index.html

The looming lockout was cited as the reason both sides wanted to make the decision. Not sure if that establishes a precedent, or if those were special circumstances.

[henr1k]

It is possible to move the date, but it has to be a mutual consent. Not sure Paul will do that, cause he would basically give C's more time to trade him.

One example i can think of is Brad Miller, he did that last summer according to shamsports. ( http://data.shamsports.com/content/pages/data/salaries/suns.jsp )