Hitting the bird from above with a slicing motion? I don't think that is possible. I know hitting from the side is possible or slightly on the side and above, but not completely above. Slicing is perfectly legal in play, but I think it's illegal on serve.
Slicing is most defenitely not illegalon service, as long as the initial contactbetween shuttle and racket is on the base of the shuttle, and not on the feathers.
If u watch Li Yong Bo's serve (when he was actively playing), it is quite clear that the shuttle is held horizontally. This would mean the feathers and the base are hit simultaneously which, I believe, is quite legal. It is definately illegal if the feathers are hit first.
