Maybe there can be a plugin or wizard written to call up the images one by one and display them while Mach runs a couple lines of code each time an image is displayed, that would be ideal but I'm not a software engineer so I'm clueless when it comes to programming.
Remember, Mach only has to run a few lines of code, basically to move the Z axis up or down a few thousandths for each image displayed. Mach is doing very minimal work here. It just has to be in sync with the images as they are displayed.
Thinking aloud.....
For each image slice have PP output a audio tone. (Speaker O/P)
Using a simple electronic circuit, the tone can be rectified and turned into a square wave pulse.
Feed this pulse into Mach to index the next Z position

??
Would that work?
ATB
Derek.