Don't really have an answer for you and will admit that the question is thought provoking.
Is it possible to change the diameter of the tool during runtime?
Well, first one would need to know some of the controller internals and that only Artsoft would know.
Instead of diameter of the tool would think that you need to reword to say "controlled point". Lathe tools have tool offsets and wear can be checked and applied to change the values in the tool table. If a drill or reamer the machine dosen't care about diameter of it since the controller moves the tool based on the controlled point for that tool.
Runtime is a little ambigous and could be taken as instantaneous change during the actual machining and not a series of machine steps where one has machined, checked / verified against some standard, make changes,and re-machine.
You need to carify what you mean!
I would also think that changing the X axis home / referenced / Machine Coordnate X=0 is a bad idea as the lathe center line really never changes ( practically speaking ).
Device.....may not need a device ....... all depends on how you want to accomplish the task and the standards that will be defined as the basis for a comparison.
RICH