if you decide to forgo the velcro method, I would strongly suggest using 3M spray adhesive “77” (maroon can). I used it. it is tacky enough to hold the headliner in place, but not nearly as strong as contact cement, so you can remove a panel without damaging it if you want to install wiring, etc. IIRC it only took one large can, which I bought at Michael’s with a 40% off coupon.