With a little help from some friends I have been able to get an up to date map of the Blackball Branch and the Roa Incline. There are still a few old bridges and stuff left today on the routes. My understanding of Roa is that most of the route was taken over by the road after the railway closed, but this could be wrong.
Here is my map embedded in Google Maps:
View Larger Map
Here is a Bing map which is higher quality but you can’t superimpose a KML over it of course. Bing only has coverage above Blackball at present.