If you just want the front of the CD drive painted, that is pretty simple. I won't go into too many painting details as those have been covered numerous times on just about every pc modding site.
First open up the disk drive, as in slide the tray out. If not powered use a paper clip or similar to manually eject the tray. If you look at it from the bottom you can see where the front cover is being held in. From that direction most just need to be pushed up and forward and it should pop off.
Then look at the bottom and sides of the CD rom drive itself. There should be a few little tabs poking through the metal casing on each side. Push those in, and the rest of the drive face should pop off.
Give em a good cleaning, then light sanding if you choose, and hit them with your choice of paint. Lightly sand between coats, and them hit them with a clearcoat to give them a bit more protection.
Put them back on in reverse when all is said and done, and you should be good to go.