I looked at the Katzeye site, and their installation instructions said something like: "These instructions are for the d300, but it is the same on the d700".
I'd be a bit wary too, Mark.
(Although I think the "can't change focus screen" is not really correct - in spite of Thom Hogan being the source. According to the web, it seemed to take a bit of time before aftermarket screens were available, and Katzeye seemed to be unwilling to produce one for a while. Perhaps "can't change" meant "nothing to change to"?)