I did read about communicating with NPD individuals before. It is slightly different, where you have to appeal to their overinflated ego.
1. Use I-language as much as possible. It defuses defensiveness, aggressiveness, and rage. I-language is non-accusatory, own's one's subjective experience, for example: "I find your comments hurtful" vs. "You are an insensitive person."
2. Compliment the narcissist, as you set boundaries. Instead of "I told you to stop calling me so much" say "You have such a nice voice, I find it so much sexier-sounding when I hear from you once or twice a day rather than six or seven"
3. Remind yourself that you are dealing with a narcissist. Remember - it is all about them, and not all about you. IN this sense it isn't personal. You have to acquire a detached, bemused perspective of the narcissist.
4. When possible, validate/recognize the narcissist's concerns/expectations, as you establish and firmly maintain your boundaries.
Instead of "Are you kidding? You expect me to take responsibility for that?" try "So you feel I'm the one who dropped the ball? Okay I see it quite differently. And I'm not real comfortable taking the hit for this."