A tutorial link is below. But, those instructions didn't work for me. One thing that I didn't understand from the beginning is that the vanes and the body-color trim are two separate pieces. Once you understand that, pushing the vanes out makes sense. But mine were very very tight. (MY'99 - been attached together for 8 years) I finally pulled the whole trim piece out with the vanes still attached using brute force. The body-color trim is held in by a tab in the lower left corner, that's where you'll need to concentrate on pulling if you do it my way. Even with the whole assembly out of the car, I found it difficult to separate the vanes from the trim. I did manage to separate them, and wash both parts. Reassembly exactly as the tutorial shows worked fine for me. Put the vanes back in first, then the body-color trim fits right into the vane assembly. Finally, push HARD on the trim in the lower left corner to snap it into the body.
http://www.ppbb.com/boards/ppbbphp/showflat.php?Cat=&Board=ARCHIVES&Number=820409&Forum=ARCHIVES&Words=10min&Match=Entire