Alright, I want to put this one to bed once and for all. I've created that account specifically for that reason.
Ky is pronounced like hi with a K. It comes from Kai Hansen, who was a guitarist for Helloween.
Kiske is pronounced like kiss and the Spanish word for what - qué. So it would Kissqué or Kiské (alternatively: Kisk'e'). It comes from Michael Kiske, who was the singer for Helloween.
Michael Kiske is one of, if not the most, my favorite singers and it was painful for me to hear it pronounced incorrect.
