Actually it is pretty much dead center in the middle of the hump. I have never had to clean one out personally. They come out in the center of the hump under the car and are situated above the cat and the heat sheild above that. From inside the car you could probably access it if you removed the center console and the black plastic shield that is on the passenger side of the hump. There is a rubber hose that makes 2 90 degree bends to get to the nipple that actually goes through the body. It comes out of the evap case, makes one bend and goes for a couple of inches and then makes another bend straight down and pops onto the end of the nipple that goes through the body. To clean it out I would imagine that you should remove the hose and blow through it with compressed air and then plug it back onto the case and blow through it again and that should take care of it. If you feel you have so much crap and crud in there that this is a necessary step then you had better make sure that you have a pollen filter installed.

Good luck,
Mark