I've done this quite a few times now. THe first time I just used degreaser and a rag and got most of the dirt off. But there was so much there. So, I took the coilpack cover off, packed it with absorbent towl stuff, then put it back on and blocked off everything important. Then I sprayed degreaser everywhere, and let if sit for while so that it really started cleaning up... Then I sprayed it off with a hose. I wasn't too keen on using a water compressor though just because of the electrics.
Since then i've pretty much done all that, except I didn't have to do it 2 or 3 times (degrease, rinse, degrease, rinse) because there isn't THAT much dirt.
Aftwards if you want a really nice shine (and smell...) then spray 'inox' on stuff (especially rubber things) and it gives it all a real nice glow. It only really lasts a couple of weeks though, so I wouldn't really bother unless you were going to a show and shine or something....