with or without ballscrews for cnc conversion mill

please I need information about conversion milling machine to CNC. I
will buy a warco major machine, but I don't understand how it will
be possible to get a accuracy (1/100 mm) without to change the
leadscrew and the bolts on Y/X/Z axis by ballscrew.
If I am oblige todo that, thank you very much for the place where
it's possible to find it and aproximately the price.
thank you very much
florent