Very easy to do. If I remember correctly,you need a 10 mm socket,preferably a flex handle rachet,and you turn the front bolts counter-clockwise( turn them up "into" the spring.)They will only turn so far, and they will bottom out.On the rear, you turn them counter-clockwise also, but you are lengthening the bolts by "backing off" the nuts. There are two clips to stop the nuts from backing off. Do not bend these( they are very fragile),but you can back the nuts off till they almost touch. Take accurate measurements before and after. I know the frt you can do without even jacking up the car. Not sure withthe rear, but very easy on a lift. Happy Lowering!
The dealer can do it. If you have a good front end specialty shop in your area, they could probably handle it also.I would ask around. Talk to some of the local "High Performance/Car enthusiasts. Found out who has a good "front end man". Good luck. As low as my car is, the alignment wasn't off enough to cause any tire wear. So it isn't urgent.
I lowered my Z06 about 7/8" front and 3/4" rear. To get that much in the front or rear you must remove the bolts and cut off one of the rubber cushions. This requires taking apart a bunch of pieces in the front.
After lowering that amount, the rear negative camber had not increased that much, so I did not change it. The front however picked up a lot of negative camber, so I removed some. That made it necessary to adjust toe. (I do alignment myself, its easy.)