How do you screw in double-ended screws?
Since the double ended screws are typically for attaching two wood surfaces together, start the screw in one of the pilot holes (just enough to stay put). Then align the other pilot hole and spin one or both pieces of wood together.

For example, if this is the below end cap on a wood pole, you'd put the screw on the end of the pole so that it doesn't fall and then spin the cap on until the screw is embedded in both surfaces and they are tight together. The only time you need to use pliers on the center piece is if you need to remove the screw.