You can also do it with some adapted spacers and an bench vise (if it opens wide enough).

One thing to be aware of, you can only press one race in at a time, otherwise both races will cam over to one side. I prefer to press the conical upper race since that's the stronger configuration, then I press in the lower cup. For most headests it's important that the press bears on the inside of the cup directly over the section that goes into the tube. Pressing on the lips of the cups can crack or distort them. (That's what those stepped sleeves on the Park press are about.