Sorry, the install was really straight forward and I didn't take any pics. I'm sure if you look around on the site you can find a general walkthrough for a spring install. Like I said it was straight forward and not difficult at all. The only hard point was busting some of the bolts loose.
As for using the wagon springs in the back, I don't have anything extra in my trunk but I do know that the JDM wagon springs are set to handle the extra weight (around 50lbs) of the wagon rear end. So with that being said, if you think you got around 50lbs of extra weight in the back end it makes sense to use those I would think. Just my two cents, never seen anyone who has actually put the wagon rears on a sedan.