Please explain their communication style and how it is different.
As a person on the PDD spectrum, let me share some things as far as relating to me goes. Not all of these may be true for others with PDD/Aspergers/Autism.
1. Thoroughly explain reasons for things, particularly if they could come across as punishment or a penalty. Since they may have difficulty with trusting others, you'd need to be more transparent than with other workers and not feel you are being questioned, disrespected, or insubordinated against by this person. You'd have little to fear if this requires revealing a few sensitive details since most of us tend to be too naive to misuse information to hurt others.
2. Learn to accept their quirks and not think of them as disordered.
http://www.autismtoday.com/articles/What%20is%20Neurodiversity.asp
3. Do not assume that temper explosions are deliberate or thier fault. Nor assume that behavior will keep escalating. Also, do not treat them differently after some episode that they could not help. Trying to "prevent another episode" may actually cause one. If they feel like everyone is trying to control them, they may explode, and if your solution is to steal more control from them, you would be feeding into the problem.
4. Make sure that the person has allies, people who will stick up for them if they are being harassed or verbally abused.
5. Watch out for them and make sure they are not scapegoated by others. Their lack of subtleties may make them easy targets for scapegoating and black-balling.
6. You may wish to inform others to not intervene if this person does anything, but let you be the sole person to handle this.
7. Don't make a big deal about their emotions, judge them on their emotions, or comment on them. A statement like "You look upset today" may come across as an accusation, nosiness, or judgementalness.
8. Keep reminding yourself that their gestures may not match what they are feeling, if anything. So you'd need to learn to pay attention to the words, not the body language. That will be a challenge since up to 70% of communication is body language. The person with Aspergers might make up for this deficit by using more words, and you might find them tiresome to communicate with.
9. If you become friends, do not use anything they share with you to harm or penalize them in the work context. I am not sure, but trying to compartmentalize work and friendship probably works the best. Don't cross consequences between one or the other.
10. If they do something beyond their control, don't punish them for their disability.
11. Don't be arrogant, belligerant, or "my way or the highway" with them, and don't expect them to change who they are or how they communicate.
12. If they need to say something in order to keep from exploding with emotions, let them, and don't let others try to control them or get in their way while they are doing this. Consider that a top priority. Would you rather "waste time" helping someone or waste time mopping up a mess that could have been avoided?
13. If there is an explosion, maybe the best thing to do is stay out of the way and avoid any inclination to intervene. Trust them to handle their own emotions and deescalate on their own. Don't play hero or the tough guy who gets the last word nor allow others to do so. Don't make it into a contest of urinary skill.
14. If you must brush them off, do it politely. "I don't have time for this," is not a polite response. If they are needing compassion, even if you don't have time, "I'm sorry to hear about that" in a sympathetic tone goes a long ways.