I don't know why, but it seems basically impossible to get to Kosice direct from Krakow. All connections seem to be from Prague, Budapest, or Bratislava.
I've heard that I can go to Zakopane, and take a shuttle bus through the mountains to the Slovak side, then scurry my way about there? Can somebody who's done the trip describe to me their itinerary that worked for them?
It's a bus unfortunately, but at least it's direct.
You can also go by train, which is much nicer. It takes a couple of hours longer and you will need to change.