Timing Pulley type:
Norman, Knaell made a commercial set of toothed pulley types for the Taig lathe. Doesn't seem to be around any more, but pics of it still can be found and will maybe help you figure out a similar system.
Go here and click on the picture links:
http://www.cartertools.com/minimech.htmlThread Copying Type:
Deciphering the photo above that I attached -- it consists of:
1.) A long steel push rod that passes through a bushing on top of the headstock and one on top of the tailstock.
2.) Brass collar stops on that push rod at headstock and tailstock to limit its movement to the length of the "master screw" when resetting it.
3.) A follower toothed arm that sets in the master screw.
4.) A lathe tool holder attached to the pushrod.
5.) An adjustable vertical steel rod that serves as a rest and support on the topslide. I see a wingnut on the topslidethat retains a smooth plate. The end of the vertical rod slides along that plate with the topslide stationary, I believe. I think this rod sets the depth of cut. Not sure how pressure is applied to the lathe tool, but maybe it's just the weight of the attachment.
That's pretty much it.
Master screws could be made up on another lathe, and in some cases could be made from commercial threaded rod for the larger common sizes.