I think it's likely JWT has onboard software which have been programed allowing the telescope to go where it's told from earth. I would also guess it would be easy to program JWT with every object and location Hubble has ever imaged or just the top 50 of interest. I also think the entire mission could be preprogrammed to locate and image objects from Hubble's existing data/coordinates, spending time on each object long enough to obtain good images. It would save a lot of time, avoiding having to for signals from earth
I just can't see JWT needing Hubble to image or locate any targets of interest, especially when the Hubble data and target locations can be readily programed or sent to the scope.