Not much to it besides pulling a couple screws and taking it off. Been a while but I believe you've got one or two tang screws then you pull the but plate and use a long screwdriver to pull a bolt that is way up inside the stock. Pull the old one off and shove the new one on. If the new one is overly tight, you might have to do some light sanding or filing.
By the way, what are your plans for the stock you are taking off? I'm looking for a take off to cut down to youth size for my boys rifle. Might be interested in yours.