I'd suggest you follow the basic steps of hostage negotiation.
1. Establish rapport (get him to trust you and to feel that you understand him)
2. Isolate the subject (this gives you the upper hand of controlling all external resources such as foods, lavatory and place to rest)
3. Find out needs and background (he might want eat or drink or talk to a relative)
4. Fulfill basic needs by trading (since the subject is isolated you can control the flow of mercendise he require, make sure not to give away anything without getting something in return)
5. Convince the hostage taker to give up or terminate him by SWAT team effort.