First, you remove the wheel hubs from the car. This requires metric wrenches, sockets, ratchet drivers, and a torque wrench. You'll need a couple different pliers and pry bars too. The hubs contain the wheel bearings. The procedure is not so difficult from here but too many steps involved to list to install the bearings.. I suggest you take the hubs to a machine shop and let them handle the bearings, they can get them easier than you. Then put it all back together.
Or get a Toyota specialist to do it for you.
If you want to find a specialist, here's a directory link for you: