[vectorit]

I did it with the new headliner.

As for the original, I can't see doing it any different.

The front panel has to be slid forward into place, and the rear has to be slid rearward into place.

The two middle pieces go straight up in, no sliding into place for the most part.
Basically push up from the middle, and then fit the ends into the channel. Once that is done, screw in the single middle screw and then snap on the plastic trim to hold everything in place.

If you can get someone to help you, I highly recommend it!
The panels are big and floppy, and having and extra set of hands to help is a huge bonus.