I mentioned them last week. There is a fair chance that they will work. This is especially true if the Big Boss is a clever man and he probably didn't get where he is by being stupid. If the facing-down tactics don't work, get a lawyer and settle for the best exit package that you can. Remember it is his loss and the firm's, not yours.
Flattery is a great technique.
Use it liberally. It is free, although it may jar your own ego a bit. But use flattery most on Elephants. They love it. They believe it.