I just called Katzeye and they said that the k10 and k100 use a different "chamber" and are not the same and are not interchangeable. And, Pentax does not make one for the k100d.
I don't know if this helps you but they said that a steady-handed owner could install it themself. Any of their screens can have just about anything on them. You don't have to get the prism focusing screen, although that is their main strength, you can get just the gridlines with any of the other options or none of the other options. Each screen is custom manufactured to the customers order and that takes 3-4 weeks. If you have them do the install you don't send your camera in until notified that the screen is ready. At that point it is about a week turnaround depending on where you are located.