By 'universal air filter' then im guessing its a conic shaped filter sold as 'to fit all cars'? Try visiting the K&N website (
K&N performance air filters, K&N elements, K&N 57i induction kits) and find you car model. You can then access the fitting instructions for the K&N product (same process).
Just be wary however, as I have heard that universal air filters can have adverse effects on performance through poor/inadequate filter elements restricting air flow etc.