Joel,
I just cleared mine. Found this blog.
http://johnnydopefish.blogspot.com/2...and-clear.html
I followed it closely, but wasn't getting the water gush i expected. So I took a can of compressed air (usually available at radio shack sold as keyboard cleaner) and blew back into the tube. If you end up having to hold the can sideways, make sure your keep it still to keep from 'icing' the rubber hose.
I also used a large shallow bowl to collect the water before replacing the hose because I wanted to see the gunk come out. Had about a 1/3 of a gallon of liquid. I was just starting to get dripping into the car after hearing sloshing in the vents for a few days. If your problem is more severe, you may need to be prepared for more water.
John