Sorry I wasn't clear enough. I know we can't control the actual zoom in FL, hence my thought was to change focus during an exposure.
The idea is to focus at just beyond the HFD so that moving the focus by, say, step size 2 or 3 will change the image because of 'lens breathing'. This will give an ICE effect.
Thus 'all' I'm trying to do is to start an exposure and change focus, i.e. coincidently.
But my gut felling is ML, or Lua, can't do this.