Yes the player would have to be in on the deal, they couldn’t be forced against their will. But if you think some players wouldn’t participate in this kind of “cheating” you’re kidding yourself. It would be just like when a player works out a new contract with the team trading for him in order to facilitate the trade.
I disagree that it's anything like a player working out a deal with the team he's being traded to. That's to benefit the team so that they're sure they're not just getting a rental of someone on an expiring contract.
If teams were willing to go to these lengths to circumvent the trade deadline, why wouldn't they just make a trade before the deadline so that the team that's releasing the player actually receives something for them? In your scenario, the team releasing the player has absolutely nothing to gain by participating in this.