I'm sure you've done this already, but maybe this info will help out others. I just put in 1.5" rear spacers on my ORG today.
I did the first side by jacking on the hitch receiver with a couple blocks of wood for extra height, which worked well. Took out the lower shock mount bolt and unbolted the sway bar link on both sides firstly.
2nd side I used the frame ahead of the rear tire which gave more clearance than the hitch BUT at the cost of stability, which got squirrelly enough to be a problem. The other side was on jack stands and I could feel them begin to tilt because of the heavy lean.
So in the end, I would recommend using the hitch to heave it up, but you'll need a tall jack. Nice and even weight spread. Save yourself messing your pants.
And to actually answer your question:
I found spring compressors necessary. You could maybe find enough room to pry out the spring, but getting it back in AND on top of the new spacer I don't think could be done. Maybe NON ORG springs it would work since they are a bit shorter. I put the compressors on AFTER I lifted the body up. Way more room to work with and the wider you can spread the compressors.
Long answer, but hope this helps someone.