Well I just did this last night. I found NOTHING needs to be removed.
Jack the truck up by the control arm
remove wheel
put jackstand under frame
put spring compressors on, compress
suspend the spring up with the help of a strap
lower control arm with jack, then STAND on it to lower it sufficiently
remove allen screw
slide that shit up and voila. done.
one thing that helped - once the allen screw is removed, jack the control arm back up to seat it with the spring and slowly lower it again, using the help of a hammer lightly tapping the retainer up so it moves with the spring as much as desired. My spring was a bit compressed "outward" so the back side was touching the shock assembly, making it impossible to slide the retainer up in it by hand. Using hammer taps kept the retainer sliding up with the spring as much as desired.
one thing though - after the first was completely finished, I noticed I forgot to put that little stupid allen screw back in. DOH! So I left it out. for now.
That won't hurt anything, right? Seems they are a bit redundant, especially with mid perch as the spring is stiffer