I cut the plastic welded button heads off with a Dremel. This is a one-way modification, as it is assembled with melted plastic.
Then, I used self tapping sheet metal screws into the barrel posts of the original mounts. No problems.
Yeah, my Florida and Texas 2006 had that gloopy broken-down glue residue, as well.
I scraped as much as I could get off with a credit card and nitrile gloves. It still didn't want to adhere to the spray on headliner adhesive I used.
I might suggest spraying or soaking in Goo Gone to really get that stuff off all surface areas, if you are going to spray on adhesive.
I did a crappy job of cutting my headliner replacement, so the hatch dome light exposes cut marks at the corners. I keep thinking that I will have it all taken apart and professionally redone, someday. It might be worth ot to consult a professional auto upholsterer.
I planned on wrapping the inner portion with carbon fiber or something easier to deal with.. sadly that won’t happen with this one. It really doesn’t look that bad with nothing. Looks like the under side of the hood.. it’s all painted... I’ll look for another one tho