So, using ACP Expert for Spectroscopy is not immediately obvious to me ....must be a way.

Main imaging camera is busy taking a picture of the spectroscopic data taking a picture of the star of interest who's position is critical.
In order to get that star absolutely centered somehow its got to be plate solved....but your plate solving the autoguider not the main imager
Once the star is centered of course the autoguiding can happen as always. Remember it can't be any star its got to be THE star.

I was thinking of how to get ACP to plate solve the image in the auto guider and then autoguide off of it but just couldn't come up with a solution

Basically what it comes down to is I need ACP Expert to all the gear, move the scope to RA and DEC given, plate solve the autogider image, put the star dead usual...then autoguide off that very image. While taking a image with the main camera. Keep in mind the autoguider here will have a very wide FOV.

Has anyone done this, if not can ACP Expert be modified to do this? Pretty pretty important.