I had to remove my headliner to have some PDR work done last summer, and it was a total PITA.
I used a write-up that I found in the regular 3 How-to area as a reference for the removal and installation. Almost all of the interior trim except for the front seats and dashboard have to be either removed or at least un-clipped...
im wrapping mine in black suade with red stiching along the edges to match the interior. ill also be swapping the cloth inserts for something else as well. not a fan of cloth