Below are directions. You do need a press to press out old bearing and hub, and press in new ones. I have seen where people use a hammer and large socket or hammer and chisel to remove the old bearing and install new one. These come in on tow trucks after new bearing either seizes or comes apart and wheel falls off. This is because either the inner part of spindle is damaged during removal, or new bearing is damaged during installation.
If you have a Autozone or Discount Auto Parts nearby, you can rent an on the vehicle press called the Hub Shark, and then do this job properly at home