i have a jinfinance split image screen in my K10D
was really hard to install,.
took all of 5 minutes.
I will admit though, I had practice as I had swapped the K10D and *istD screens already once for a metering experiment.
It is really easy to do with tweesers and a small jeweller's screqdriver.
As others have posted, jinfinance screen needed no shims or adjustments, and the split image is spot on with the camera's AF.
remember to take the protective plastic off the screen before installing.
One comment on the screen is that it is a little "rough" around the edges. The diagonal line for th esplit image does have some flaws in it but they don't impact function.
Also note if you thought meterins is bad with manual lenses and the stock screen, it does get a little worse, especially spot metering with a split image screen.
As for focusing, it is a joy to use especially wit my newley aquired 85mm F1.4 (samyang AKA vivitar)