What i'm really getting at is, if we had a guy like Carmelo willing to sign on the dotted line and it all came down to moving Wallace and Lee. Would it give us the cap needed to offer a max deal?
The scenario you are probably looking at is what Golden State did to sign Iguodala. They could send picks to Utah so that the Jazz would take on the contracts of Jefferson and Biedrins with their extra cap space, creating room to sign Iguodala, so Denver was induced to agree to a sign-and-trade so they get a little something out of the deal.
The best scenario for the Celtics to sign Carmelo Anthony if he wanted to come to Boston is to find another team which would take on Wallace, Lee, and Bass for the price of three firsts and a couple of seconds so that there was cap space to sign a big free agent to a contract, then go to the Knicks, point out they will lose Melo for nothing, but if they agree to take back Wallace and Lee, the teams can do a sign-and-trade for Melo and give the Knicks some picks (but fewer than the other team would get for renting out cap space). If the Knicks want to slash payroll, you can use the unguaranteed contract of Bogans as part of the deal. Maybe a free agent such as Kris Humphries would be amenable to being part of a sign-and-trade, if they like him.
That way, the Knicks get assets to rebuild and the Celtics don't have to send out as many picks, possibly retain Bass and his expiring contract to be used in a future deal (or to keep him as a useful player), and don't have to renounce the trade exception from the Nets trade, which they would have to do if they used cap space to sign a free agent.