1. Hire a good lawyer and get good advice. The best defense is a good offense and all that.
Make sure he has no ability to use company funds. Cancel his company debit / credit card if he received one as a director of sales. Send an official letter by registered post letting him know that he does not have the ability to authorize expenses above $100 or so.
Then follow your lawyer's advice on firing him from the sales position.
Make sure your lawyer communicates the non-compete part with him properly - so that he realizes that if he leaves now, he won't be able to profit from the idea at all - and its better to stay with you and earn 22% of the pie than go for 100% and get a big fight on his hands that he will most likely lose.
2. > The person had a large rolodex in a segment of our market.
This tells us that the person's reputation can be adversely affected. Threat of bad press could maybe get him in line.
Also, it would be a good idea to find at least one or two common connections and try making them mediators.
3. This is the stick. You need to offer him a carrot too.
Make him an offer: he does not work with you. He retains his shares and plays a role as an investor. He gives up the board seat - and remains a silent investor. He gives you a connection / letter of referral for all the contacts he is sitting on - for a flat fee. No vesting of shares.
Position this "getting a fee for writing a letter of introduction to his connections" - as the carrot. A lot depends on how you phrase it.
4. Start contacting other investors who could maybe buy this person's share out. I doubt if you can find and close someone in 7 days, but the sooner you start looking, the better.