Yeah, they are definately a bitch and a half to do. My stocker is laying behind my shed, I never could manage to get it apart. wound up buying a twin row carrier(has 2 bearings on each side) a G-Force axle, and used brake hub and disc. Then I coated the axle, and the sleeve inside with anti-seize and re-installed it. Not cheap, but the thing will come apart easy next time, and it should last a lot longer.
If you have access to a press, that is the cheapest way to go, and then make sure you use anti-seize when you put her back together. The Yamaha delarship will most likely put it back together the same way the factory did, and youll have the same problem next time you want to change the bearings. (if you want to keep the bike that long)