It should have came with two hooks that are used to tighten and loosen the perches the spring sits on. once you loosen them just screw the locking perches downward and tighten them once you are at the ride height you desire. I used a tape measure so I would get equal heights. Remember when you lower your ride height, your camber caster and toe will be off so make sure you get an allignment. I needed a camber kit to correct my camber, so make sure you have some extra money just in case.
the strut is like a big bolt with a big nut your spring sits on the big nut and as you turn the nut the spring either goes up or goes down. on Ground Controls you have to loosen up a little bolt inside the big "nut" and then turn I am not sure how it is on the S2 but I think you have a locking "nut" and a turning "nut" do you have a key for it?
if you mean by the wrench hooks that came with it as a key then yea... im going to get some cambers also to fix the alignment like 1996tegGSR said...so i dont have to loosen the bold thats under my hood.? im new to suspension and i just dont want to screw anything up... how low should i slam it also?