Well, to do that you need to lift both sides of the rear of the vehicle. That usually requires 2 people there.
I guess you could try the spare tire jack and a friend or the spare tire jack and a stack of bricks?
Seriously you should chock, support and jack your car on level surface and check it as you will need to go under the vehicle. You need a second jack handy to lower the lower cross member as well as raise it back up.
I just loosen the rear lug nuts, then jack the rear on the spring buckets. Put the stands where the jack points are under the rear doors. I then check it, then remove the rear wheels. Position jack under the spring bucket and undo the 15 mm bolt for the lower shock bolts, then lower the rear cross member and pull out the springs.
The bar bolts right in. I installed mines loosely til I got all the bolts in, then firmed them up. Then reinstall the springs, jack the bar up to insert the bolt in the shocks
Since you got the rear springs off, maybe consider a pair of sport springs too?