You'll have to take it apart. Pull the drive out, and carefully start disassembling it until you can pry the drive open. And don't be surprised if you need to replace the thing after.
If anyone can offer help, it would be appreciated. I have a friend with a Dell that has a cd stuck inside one of the drives. We can't get it open. We've tried the paperclip in the little hole that is supposed to trigger it open, bu no luck. Ant suggestions? Thanks!