Hi!
We do that kind of work a lot.
You need underwater positioning and a boat that can go very slow.
UW positioning can be Waterlinked SBL system or a USBL system.
By giving the skipper of the boat a screen with ship position, ROV position and waypoints there is possibility to manually hold position for a skilled skipper.
Since the movement is small you need a ship that can go as slow as 0,5 knot or less.