The key in doing these is really execution, but that's the case with most movements.

You don't want to turn incline rope pullovers into a triceps pushdown, so the elbows need to stay slightly bent during the concentric/lifting portion of the movement. And the focus should be in bringing the elbows down and into the waist to really shorten the lats against the load.

At the bottom, you want to try and squeeze the elbows together to maximize the peak contraction. Then really fight the eccentric/negative to increase force production. They're not Nautilus pullovers, but they might have to do.