If my quilt is already bound, I will "bind' the label and the stitch it down by hand on the back. If I haven't stitched the binding down yet, I'll 'bind' the label on two sides and catch the other two sides in my quilt binding, stitching the remaining two sides down by hand.
Another to skip the 'binding' on the label, you can fold a square in half along the diagonal -- catch the raw edges in the binding and the just stitch across the fold.