I would think that a decent 3M spray adhesive could be used and that you could just gently stretch the fabric over them and then trim them afterwards. My only concern would be the fire rating. Most fabric is not fire rated and then there is the glue. Perhaps there is a glue that is fire rated and you can find a fire retardant spray that could be applied over the cloth after it is glued on. I would definitely check with the local fire chief/inspector as they can be very helpful.