I would use a spray adhesive that you can get at craft, automotive or dept stores. A spray, as opposed to a tube or rubber cement brush, would ensure an even film that you definately want on these inserts. Many sprays say to wait until it gets tacky before sticking it on, so you wouldn't have to be too concerned with getting goop on other parts of your boots/shoes as you are placing the insert. 3M makes several kinds of spray adhesives - just depends on the material (rubber, foam, fabric, etc.).
Tony
August 2010