How hard is it to sew the hook part of the vel-cro onto a pair of pants that doesn't have it? I have a pair of leather pants that do not have anywhere to attach knee sliders. While I currently can't get a knee down, it probably won't be long before I do. I really don't want to mess up my leather pants by dragging them on the ground. I have heard that the hook part of the vel-cro can be sewn onto the pants to allow the attachment of sliders. Has anyone done this? Was it difficult?