Calling additional attention to her illness by trying to educate her classmates could really backfire like Musicgirl suggested. I've found a very short explaination is generally best. Something like "I have a rare nerve disorder called RSD."

If she is effected by vibrations and noise, it's really going to be tough on her. I've learned over the years it's impossible to control any public environment, and probably unfair to ask other's "normal" behavior that causes me pain. So, I'm careful to minimize contact to others, and avoid lots of situations...

For example, someone kicking the back of her desk, might send her into a major flare... She may need to have a desk in a corner away from the other students. Kids bump into other desks, and to try and "train" others, is probably impossible even if they care enough to make an effort. Another accommodation, might be for her to be allowed an iPod in class with classical music to shut out some of the stimuli--this is something I do when I travel.

Is this a large school or a small one, btw? That will really make a difference.