Lay the stock spring and spacer on the floor, lay the new spring next to it and cut the PVC spacer to match the original preload. Save the stock spacer until you're certain you're happy with the end result.
A thick blanket on the tank to rest the bars on saves scratches and cursing. A hand operated pump to draw the old fork oil out is what I used but I've read a turkey baster and hose work just as well. You don't have to change the oil, I figured since I was in there is I might as well.
Those caps are under spring pressure and want to jump off when you get them loose, take it slow and you'll need both hands right at the socket when it comes free. You'll see.
You can do it on the side stand if you're not changing the oil, just do one side at a time and push the cap a little harder to contain the spring.
