I used a screw driver ;) and 1/4" x 6-32 philips screws to bolt the rad to the case (from the top), then the stock screws (those that came with the rad) to fasten the fans to the rad (with fan guards).
Warning: DO NOT USE anything longer than 1/4" to bolt the rad to the case, or you WILL poke holes thru the rad (no warranty for that)

