How To Integrate Expert In Extreme Programming Team

Well, I've heard that XpIsGeniusFriendly....

PairProgramming comes to mind.

Specifically, Ms or Mr Genius is forbidden to drive. They may only navigate. They must explain every step. This runs the risk their delicate sensibilities are offended by not being able to do their own favorite keystrokes and they start hating life, but the alternative is to dissect their brain and put electric probes all over it. -- PCP

Or perhaps you could PairExpertsTogether?? -- MikeSmith

Assuming that the combination is not hypergolic, there is the danger that they very rapidly build a briar patch impenatrable to other team members. Depends what they are experts in, of course.