You already have blocks in the back....those were a waste of money. DO NOT stack blocks. You should do a short Add-A-Leaf and a Belltech 6400 shackle. This will get you approx 3-3.5" lift. The other option is getting 95-01/05 Explorer multi-leaves. These give you GREAT ride quality while providing approx 2.5" rear lift. They're a direct swap. Both methods require new rear shocks.
Ideally, you should have purchased 3" lift spindles. Buying new keys, while they do provide lift, they also cost you down-travel, ride quality, and ball joints. CV's take a toll big time if you had those, but you don't. Lift spindles are a far better investment in the long run.
BUT....to answer your key installation questions, get the truck up on stands from the frame. Loosen everything up like the tie rod ends, sway bar links, shocks(upper or lower, just one end), calipers. Use your floor jack to hold the lower control arm up while you remove the torsion bar adjustment bolt. Remove upper ball joint from steering knuckle and this should allow you enough downward travel of the control arm to remove the "nut" that the adjustment bolt threads into. Once that's out, you can drop the key and slide the torsion bar and key out from the lower control arm. It may make it easier to loosen the lower control arm frame mounts...just remember to tighten them back up when the truck is sitting on it's feet again. Installation is reverse and can be a little cumbersome, but this method uses NO special tools, and is the safest technique. I do not have a how-to or ever intend to, alot of it is pulling the wheels and seeing what needs removed to make the truck "droop" out to it's fullest and beyond to relieve tension off the keys.
Be careful on your adjustment bolt pre-load once she's all put back together. Note: you likely will not be able to get a proper alignment after the installation of lift torsion keys.
Proper research prior to purchasing parts would have helped a great deal here.
'01 XLT disguised as a '03 Fx4 Level II
Big. Loud. Slow. Bright.