Plan on 2-4 hours to do the job with a floor lift and jack stands.
It doesn't take some that long, but your first time wrenching on that car you don't want to rush.
It's pretty easy though.
For the rear, set jack stands under the subframes on each side, lift the car up with a floorjack under the "pumpkin" of the rear end, remove wheels (loosen lugs before car is off the ground).
Disconnect shocks (quads too), and SLOWLY drop the rear axle with the floor jack. The stock springs may need some "persuasion" to come out, but nothing a good yank can't fix. Just make sure the axle is low enough that there is VERY LITTLE tension on the springs. A kick from a loaded spring can break a lot of bones. Reverse method for putting them back together. but pay attention to where the "pigtail" (end of the last coil) sits on the control arm with the stock springs, and install the new springs in the same spot.
For the front, jack the car up and place the jackstands under the front subframes on each side. Loosen the lugs, then put the floor jack under the front a-arm on whichever side you're doing first, lift, remove wheel.
Remove brake caliper, hang out of the way, set brake pads aside (make sure they go on how they came off). Disconnect sway bar links (on both sides), disconnect strut FROM THE BOTTOM (disconnecting it from the engine bay can throw off your alignment).
Once all that is done, slowly lower the floor jack until the a-arm is fully dropped. Remove front spring, again, be careful it is not loaded, and replace with the lowering spring, installing the same way the factory spring was. Jack the a-arm back up and re-connect the strut, re-install brake pads and caliper (make sure the caliper is installed properly and bolted on well!).
Repeat for other side. After both sides are done, reconnect the front sway bar.
Annnndd... enjoy your new springs. That's it in a nutshell.
But holy ****, the Cobra comments had me rolling. Don't take it to heart, we just like to "break in" the new guys sometimes when they leave themselves open...
EDIT: You do not NEED a spring compressor to do the job. The shorter aftermarket springs will fit without much hassle, UNLESS you are going with a very minimal drop. I had zero issues literally placing my Roush springs back in, and they are not a large drop by any means. Just be careful when removing the stockers. I am serious when I say you can get hurt by them if they unload on you.