This is a famous/popular question in many Linux forums. The typical answer to the question is “Login (especially autologin) into a system as root is bad”. That’s right, but WTH! The person is asking how to do that, not if it is good or bad! If you don’t know the answer, don’t answer the question you’re not asked about!!
Anyway, if you need to autologin as root for some reason here is the recipe for Open SuSE 11.1 KDE 4.2.2 that could work for other Linux/KDE combinations: