I believe the post to which you are referring involved an OD threadder that was .006 or .008 below center on a small dia thread. Nonetheless, some machines can be locked by pushing a button (spindle lock) or in MDI; M110 or M19 or G28 C0. or M10, etc. Basic idea is to lock spindle and lightly scribe a line with a qualified face tool. Jog suspect tool to face and meaure from there. While I doubt the exact measurement can be made, an aprox is close enough. The Hardinge T42 Super Precision has a turret that has slots where a .75" ground bar can be mounted to set boring bars, ID threadders, groovers and such can be set so you can clamp the ID tools at any height-desired at .01 above centerline. Most slant beds require a line to be scribed on the face of the set-up part and tools set from there. That method is close at best.