I may be wrong, but I don't believe this is possible anymore. Teams that are over or will exceed the salary cap via sign and trade can't do sign and trades. It's why they've become so rare since the last CBA when they used to be the norm.
Teams that are in the luxury tax or will hit the tax can't do sign and trades, or acquire a player from a sign and trade. Also players involved in sign and trades can no longer receive that extra year or the higher raises that used to be available if their original team agreed to trade them off like we did with Amare. Since there really is no advantage for the players anymore in terms of years or annual salary, there isn't much reason to even ask for a sign and trade. That's part of why it doesn't happen anymore. There's less of an incentive to make it happen.