To install a cabin air filter in a Toyota, buy the right size air filter for the model, clean out the glove compartment, open the panel hiding the filter and removing the old filter. At that point, put in the new filter and reverse the process.
Specifically, to access the air filter, open the glove box and clean it out, as this is where most Toyota models have the filter. Look for some plastic tabs around the edge of the glove box. When depressing them, the glove box opens more fully, allowing for easier access to the air filter compartment. When it is fully open, look for a long rectangular strip. Locate two tabs, one on each side, and squeeze them to expose the air filter.
Remove the old air filter and put the new one in its place, ensuring that it is facing the correct way. Find the right part by checking the owner's manual or buying the part directly from the dealership. Place the rectangular strip back into place, and reassemble the glove box by reversing the instructions. With the new air filter in place, cleaner air circulates through the car when using the heater or air conditioner.