You dont have to go as far as Donut King went....
Just Jack up the rear by the diff, put stands under the chassis rails, undo top shock bolt, undo bottom shock bolt then pull out shocks, lower jack until diff comes down far enough so springs can come out (you wont have to lower it all the way)
Put new springs in, install shock with the top nut going on first(you'll need a second person for this) raise diff until the bottom bolt holes in the shocks line up, tighten bolts, then lower the car.
If your confident in doing the fronts then you'll have no problem with the back ones.
Fronts take about twice as long as the backs.
Probably take around 4-5 hours for all four from start to finish, car on the ground, tools away and a beer in hand. (thats what it took me from memory)
1993 ED XR6 M5 (1 of 329)
Turbo on the way!!
1993 EBII Fairmont (Now wrecking, PM if you want any parts)
1988 Nissan R31 Skyline