I ordered the part off of Amazon because mine was cracked. Took about a week to get here with Prime 2 day shipping. I complained and got a full refund while getting to keep the part. Even though Amazon lists this as the correct part, it does not completely match the original. That being said, it still worked out just fine. Sorry for the blurry pictures, I thought the camera had focused.
http://www.amazon.com/gp/product/B0055B04XW/ref=oh_details_o01_s00_i00?ie=UTF8&psc=1
Gather a small flat blade, a large one, and a pair of needle nose pliers.
Lift and remove the bottom of the back seat (obviously)
Slip off the old vent tube and pull it out of it's hole
Remove the grommet that attaches the tubes to the outside of the car. I was able to lift it with a flat blade and grab it with needle nose pliers. Wash it off with warm water. Using warm water will soften the rubber making installation easier.
Slip the drain end into the grommet. Mine looked like a bendy straw. I had to make the hole larger, so that is what the large flat blade and needle nose pliers are for.
While doing this my hand slipped and lifted up my thumb nail. Don't do this.
Force the grommet back into it's hole. Make sure it is completely flush with the body. You don't want an increase in road noise or the possibility of something coming in, do you? After that just slip the ends over the battery.
Replace the back seat and make sure it is seated (ha.....) correctly.