If heat is not an option, there are some techniques which use dry ice in an enclosed (but not completely sealed) container with the clothes/bedding. Dry ice removes the oxygen and suffocates bugs. But you should google more precise directions and safety precautions, and find a way to make sure the dry ice cannot touch the quilt just in case it damages the old fibers. I also don't know if it can kill all the eggs of bed bugs or cockroaches.