I'm not sure I understand you correctly but the concept is this:
meter for zone III and expose the film for this setting. now meter for your brightest highlight and this is zone VIII.
now if the brightest highlight is falling on zone IX or X, develope the film N-1 or N-2 accordingly.
if the brightest highlight is falling on zone VI or VII then develope the film N+1 or N+2, accordingly.
The reason one uses a spot meter is because you cannot get close enough to a subject such as a mountain or something similar.
I am using a Pentax digital spot meter with the zone dial. This makes the entire process effortless. I meter what I want to be zone III and then the dial tells me where zone VIII falls. If it does or doesn't determines my developement and I jot this info into my trusty little notebook.
If your meter will allow for a zone dial, get one.