actually, with a lot of the full-synthetic gear lubes out now-a-days, limited-slip additive isn't necessary, as the lubes already have them.
And it is a quick easy process. But as Al stated, make sure the fill plug is NOT frozen before you pull the cover! And when pulling the cover, it is best to NOT drive a screwdriver, chisel, etc, to pry the cover off. This can cause enough damage to the mating surfaces and cause leaks.
Obviously, may need to do a little prying, just be VERY careful not to damage it too much. And if anywhere, do the slight prying at the top; less chance of leaking if something does go wrong.
After draining and cleaning, don't forget to use a scraper to get off all the old silicon sealant from the mating surfaces. Then clean both surfaces well (I used brake parts cleaner sprayed onto a rag).
After applying RTV and when bolting the cover back on, just like your tires, tighten bolts in a star-type fashion. Also just really need to get them snug, not too tight. Then wait a couple hours before re-filling, to let the silicon cure.