quruerror,
If your headliner is not damaged, just dirty. I saw the guy change mine. It's simple. He actually covered over the one he cut the sun roof in. He had a big roll of headliner materal rolled out, it was sticky on the back side. Turned my header upside down onto it. Just cut the excess and rolled it around to the backside so the edge wouldn't show. Pushed it back in from the back.
Vern