How about making a belt loop seperately and attaching it to the belt with screws? It is what I do, and allows you to remove the loop or change its postion.
to make a loop, just take a 1 1/2" wide piece of kydex about 6" long and heat it, then wrap it around a piece of 1 1/2" x 1/4" piece of steel (or a piece of wood, or an actual belt) to make a loop. With a bit of practice, you can make a loop in about 30 seconds.