If you're installing rubber bushings into control arms that are NOT FORGED at the bushing end, you're going to push the original shells out, including the sleeves and rubber. Then you press new shells, (with sleeves and rubber) in all-together since they're a bonded/one-piece assembly. It's a pain in the asp. You MUST (!!!) have the vehicle at normal ride-height before you torque the control arm through-bolts.
If you're installing Polyurethane bushing inserts, the outer layer of rubber is melted evenly around the shell (not burned, if possible. If there's smoke, sparks, flame--it's hotter than it needs to be) and then the rubber kinda "poops out" along with the inner steel sleeves. The shells STAY IN THE ARM. Clean up the interior of the shells with sandpaper/emery cloth/scotchbrite, grease 'em, grease the bushing inserts and steel sleeve, and cram 'em back together. Typically, finger-pressure is all that's needed. You can torque the through-bolts with the suspension in any position if all the bushings are Poly.
Forged lower control arms are somewhat different in that they don't have outer shells, the rubber rides directly on the control arm. I've never changed bushings on forged arms--but that's what my '97 K2500 has, so I'll get to it eventually.