I had a bunch of these made up. You can see they allow the cable to tuck nicely.
http://www.vmptuning.com/sct/lwcable.jpg
http://www.vmptuning.com/sct/lwcable1.jpg
http://www.vmptuning.com/sct/lwcable2.jpg
http://www.vmptuning.com/store/index.php?p=product&id=209&parent=0