Covey's stuff is pretty good, but like most things it isn't a panacea. Having been a "difficult" person to manage, and having been a manager of difficult people, I can tell you what worked best for me in both situations:
1. Make sure you have clearly understood goals and objectives, preferrably written down and signed by both you and other person.
2. Make sure the goals and objectives focus primarily on overall work responsibilities and performance of assigned duties.
3. Indicate what criteria will be used to evaluate their performance against their goals and objectives.
4. Have periodic (quarterly) informal evaluations of "where they are" against their goals and objectives.
5. Have a game plan before any evaluations, and make sure you carefully choose the words you'll use to keep emotion out of the discussion. Just like a difficult child, if a "difficult" person senses that you're action from emotion instead of a firm grounding in rules, they will immediately use that against you in the conversation, regardless of whether you're right or wrong.
6. Make sure you're intimately familiar with your HR policies concerning counselling and discipline of employees. Many managers (and companies) have gotten into trouble for not following the laws (or even their own rules and policies) for handling "difficult" employees. Usually, the company ends up on the wrong end of the stick.
Just my two pennies, but it isn't much different from the various strategies presented here on CD about dealing with difficult child's. The only difference is that you don't have the emotional attachment to the person driving you insanity. If you keep the emotion out of it, keep the message simple, on task, and easy to understand, it makes it much easier on both you and the other person.
Mikey