Microwave them in water to soften. Press into the drop links using a bench vise, C-clamp, or large (water pump) pliers. Remember that they enter the drop links from opposite directions.
A little lube helps here.
When pressing onto the ball joints of the bar or the lower shock bolt don't use lube in the socket, it can form an air seal
preventing the socket from pressing onto the ball. Working on jack stands, I used water pump pliers to seat the drop links onto the balls. If you're working on a lift and have room to work under the car, I've been told you can use a long screwdriver or bar pivoted up in the wheel arch to lever them on.
Harvey