Uppers or lowers?
Lowers: cut out the originals, get some 2 x 2 x 1/4 angle iron - make some precise fit spacers to go in between the two gaps. Note that due to stuff moving around and being old you might have 4 different lengths cut for the 4 lowers, but odds are you're right and left will be the same. Just make sure you have it snug enough so that it won't fold and then press it in.
Uppers - You can press the first in normally, then drop in the second, make a long spacer so you won't fold the control arm and go to town pressing that one too. I have also had one or two urethane bushings that I could press out of the housing with persuasion so I could press the uppers in normally, then drop in the urethane and use the cross bar as a press of sorts to draw in the urethane.
Just my opinion - I've read about doing uppers while they are still on the car using heat and a hammer, but I'm a little leary of putting heat into the control arms.