FYI - I changed my cabin filters when I did my last oil change @ 19k. The car was on ramps, so there was not nearly as much contorting to do to get to the screws. I was dreading this based on everyone's expression of discomfort involved. But, I can tell you that the front end being on ramps made it very simple. A stubby philips head screwdriver is a must for the top screw.
Pay attention to how the old ones come out. Basically put the top one in first (foam gasket side up, finger tab facing you), slide it up to the top of the housing and hold it in place with your right hand, then slide the lower one in with your left hand, making sure the grooves of the two filters slide into each other.
Seariously, it took no longer than 5 minutes for my first time doing it.