This is what I have done - you know how most people wrap the wire spiraling down the front brake cable? Well I do that, and then I run it to my derailleur cable, and spiral it down the naked cable all the way down to the bottom bracket/chainstay. It is much nicer looking than having zip ties all over the downtube. Only thing is that you have to be careful that the wire does not bind to the derailleur cable when you shift. I will post a pic when i get the chance.