On the Saturn, it was like a plastic rivet. A 2-piece affair. One half of it had a pin-like appendage, and looked like a thumb-tack. The other half had a hole. You stuck the pin thru the web, and snapped the other end on it, then snapped off the tip.
Heck, go to a Saturn dealership and get one, I'm sure it will work. I was able to explain it to them well enough, and they got me one. It was in stock, even...