Chris,
Not sure if it is in the same place on an 03 as it is in my 98 bug, but I suspect it is. Access it from inside the car, just in front of the passenger seat. You remove the center plastic shield - top center of dash, just under the windshield - by sliding it toward the front of the car. You will then see the screws to remove the panel just in front of the passenger side seat. They are torx screws. Under that panel you will see how to remove the rest of the filter. It's a little tight in there - but hey, that's a bug!
Kirk