stock rear shocks work ok with OME lifted springs. bilstein shocks of the srock lengths also work ok and you don't have to have OME srings to install them.
As to installation of the rear springs it pretty much straight forward. how I did it. I disconnected lower bolt form the shock then loosened the inner bolt of the arm that the spring goes to and installed the spring. The inner bolt goes through the bushing which is offcentric and serves for allignment. so when you chnage the spring you would have to reallign properly on a computer equipment. in order not to go far off the proper allignment i marked the position of the arrow. it turned out that I was pretty close after bolting everything back together. Also I would drive few hundred miles before making the aallignment other wise you would have to make alllignment again after the spring sag. Mine sagged about 1 - 1.5 cm in abot 200-300 km.
I also forgot that you would have to disconnect sway bar links too to put in new springs.