Search in the mechanics forum for internal cable routing and there are instructions on how to use the vacuum/string trick as well as other ecommendations. Basically, you feed a string in the easy end and then apply a vacuum with your hand cupped around it to the other end to suck it out the hole. You can then use the string to attach to your wire and pull it through to the other end. If you have a small housing you can use, you can feed that on the string until it is out both ends and then feed the wire through that. At that point, whenever you need to change either the wires or the housing, you do one or the other first, using the other, which is still in place to feed it on or through.
Last edited by Ciufalon; 01-15-11 at 03:10 PM.