Don't know about Y2K though. Note that at best it is an iterative process. The Mark IV is not a precision mount. This should repeat to 0.1 milliradian. So one can take some data, compare it to time, and get RA right to a couple of seconds of time.
Declination is another matter.
I do not expect it to be very good. The stop will be good to about 1 milliratian. So if you are sitting on the stop it will be that good. Moving off the stop is done by counting steps. It is a chain drive and wobbles a lot.