Any question answered...

Thank you.
Specifically though, with routers not designed for it - assuming you can fox the housing of course - there's no reason why you can't?

Nosier: I assume you are talking about only running the inner cable along the top tube.

If that's the case then you can but it can damage more quickly. You would have to make a stop in the beginning and at the end so the outer cable won't move. It's easy to do, just not the smartest thing to do.