Actually the rails can be bolted in any order, rear bolts do not have to be done first.The rubber things go on the passenger foot peg brackets and the cases slide into them to locate.
Under the tool kit you will see 4 bolts the thread into the rear fender. Undo them and two bolts just in back of the battery on the left and right side of the plastic under tray. The under tray should be loose but its over two tabs at the front. You have to spread it out slightly to lower it.
After you lower the under tray you will see a cut out on each side to follow that you have to cut out to mount the rails. Cut those out. Put the back bolts in where the cut outs are first, then the front bolts. Oddly they have to be done in this order. Also it's easy to get the front bolts cross threaded because everything is a tight fit. So make sure you hand start them.
BEFORE YOU DO ALL THIS PUT SOME TAPE OVER THE MOUNT FOR THE SHOCK ADJUSTER AND THE UNDER TRAY TO KEEP THE ADJUSTER FROM SCRATCHING THE UNDER TRAY. The ECU is bolted to the under tray. You can detach it or just be sure you don't strain the wiring to it. I had enough slack that I didn't detach it.
Much easier to view than the paper version.COMPLETE INSTRUCTIONS CAN BE FOUND HERE:
I found this by going to the Kawasaki website, clicking on accessories, then inputing the bikes year and model. Then I selected the accessory, and there was a link for the instructions.