I have been put into a win-lose situation lately (me=lose). First, it is a good sign of bad faith of who you are dealing with or bad lawyer advices. A bad layer will advise you to push a win-loose deal it is most likely going to end in a lucrative billing lose-lose situation for him. So please, fire your law firm if it is happening to you.
A lose-lose is the biggest wealth destruction you can go so you need an alternative sometimes when you need to choose your battles. Now, how can you turn a win-lose to a win-wing?
Accept the win-lose but transfer the lose to a win later on. Make a side deal or informal deal so they own you one. Transform an enemy to an ally later on.
If you are badly advised, you might be stuck in that situation and might be willing to take the risk of been able to make a win-lose proposal pass. Don't forget that all deal should be a win-win, its ensure failure is not a option (win-lose to lose-lose).
There is a rule to succeed, ensure failure in not an option.
Last, before taking the risk of pushing a win-lose, ensure yourself that the other side won't take the challenge, they might have nothing to lose or might have super ego but why taking the change. It is basic risk management. If you end up in that situation, your management team isn't doing its jobs. Someone has to be fired. If you decide to keep the management team who put you in that situation, you might want to force them taking sales classes and basic human psychology.
Win-lose is definitely the best way to destroy trust and without trust it gets messy. Don't forget, people hate losing and might be spiteful so why taking that risk, it is a wast of time and energy. Why taking the chance of underestimating who you are facing instead of a win-win which is eliminating failure alternative and is optimal energy and time wise.