I used this method on my Chevy G30 but it should work on other vehicles.
Remove the pin and loosen the nut on the lower control arm bushing. Leave the nut on - just slacken it off enough to break the joint.
Put a jack under the lower suspension A arm and jack it up.
Find a suitable sized solid metal object that wont crush or shatter and put it in the gap. I used a socket. It should be a fairly tight fit.
As you lower the jack the gap becomes tighter putting all the spring pressure on the ball joint. It should pop out with a bang. The nut will stop the lower control arm dropping completely. I did have a nut on there when I split mine I just redid it for these photos hence no nut in the photos.
Now with the jack still in place remove the nut and lower the jack slowly until the suspension spring is at full length.