Got my Katzeye yesterday and installed it in my T1i today. Do not try this without a good lighted magnifying lens if your eyesight isn't really good. I have a so-so lighted magnifier and it was a royal pain trying to see what I was doing.
That said, I did eventually get it installed properly and I think if I have to do it again, it would be easier. I'm fairly happy with the results. Below are some comparison images with 100% crops. These are SOOC with no corrections (as you can tell from the CA).
Auto focus and 100% crop.
Manual focus and 100% crop
One more manual focus with crop.