This is easy, I just completed spray-painting my floppy drive, two DVD drives and Aerogate II.
You want oil-based matt black spray paint. Glossy looks weird, matt black is about as close to normal black-painted cases as you can get. You don't want charcoal-black 🙂
Pop the drives' trays out, remove the front piece (usually two little catches holding it in place). Remove the bezel (again, usually two catches, one either side, or sometimes one on top and one on the bottom as well).
Remove (if possible) the eject button and the activity LED. It's much easier to remove them than to mask them off. If you have to break the lugs holding them in place, don't worry, you can get them back on with a tiny dab of superglue.
Clean the components with soapy water- you don't want any cigarette mess or dust on the parts when you're spraying. Make sure they're thoroughly dry first.
If you haven't spray-painted before, here's how:
Lay down some newspaper outdoors, and shake the can for a good thirty seconds or more. From a distance of about thirty centimeters, spray one light pass over the drive. Do not go back and fill in bits you've missed, you want to build-up layers, otherwise you get paint drying in lumps, and you won't get a smooth finish. Leave paint to dry for about 10-15 minutes. Ideally, you want a speckled coat that looks terrible at first glance, but dries quickly. This is fine- from personal experience, if you try and get it perfect the first time, the end result will be a lumpy finish with paint clogging the drive emblems (such as the "DVD-ROM" bit on the end of the tray cover.
Go back and do another coat, let it dry. Repeat again, and then concentrate on the sides and reverse of the components. You may need to wrap a plastic bag around your hand so you can hold the bezel and spray it without it falling over. Make sure you do all this in as much of a dust-free environment as possible, as you don't want little flecks on the paintwork.
Leave to dry for another half hour or so, and then, if the paint's dry and hard, refit the components back into the drive. While the paint will "skin" in half an hour, the paint underneath won't be 100% dry, so take care when refitting, or just wait a couple of hours.
Result? Black drives 🙂
Oh, last but not least, you probably don't want to paint the tray itself. Reason being, there's a chance that the heat of the drive spinning could have weird effects on the paint on the tray. Best to keep it as original as possible, and you'll only be seeing the tray when you have to put a disc in, anyway.
