Where you live has nothing to do with the emissions certification of your vehicle. If you still have the emissions tag under the hood, it will let you know if your vehicle is emissions certified for California or not.
Assuming it's the one bolted to the exhaust manifold, make sure you have a new gasket, 20822-7J610 and 20840-7J610. Easiest way to do it is to remove the exhaust manifold with the converter and swap it over on the bench. This means you will need a new exhaust manifold gasket and you "may" end up needing some exhaust studs and/or nuts. Most of the bolts and nuts will be 10mm, 12mm, and 14mm. You will need to unbolt the front pipe and remove the bracket attaching the bottom of the converter to the engine block and unbolt the manifold from the head. You will have to unplug the O2 sensor. You "may" have to loosen or remove the alternator if it's in the way. Remove the manifold and converter assy. from the top. In my experience, the bolts that attache the converter to the manifold are easiest removed with an impact gun. If you need to remove the heat shields, often the 10mm head bolts that attach the shield are badly rusted so a 10mm socket or wrench will just slip on it or the bolt will break. Since you are replacing the converter, broken shield bolts aren't a big deal. They are 6mm X 1.0 if you need to replace them.