The full mounting handbook can be downloaded from the Rohloff websitehttp://www.rohloff.de/?lang=en&p=DOWNLOAD/Beschreibung&d=
They supply plastic clamps to hold the cables, but looking at the pictures they are as ugly as cable ties. If it’s a steel frame, any frame builder would braze cable guides on for a few quid, then you’ve got the expense of a paint job.
I looked into retro fitting a Rohloff to an existing bike. It wasn’t worth it, even sourcing the hub in Germany where it’s a little bit cheaper and using a lot of components off the old bike, the result would have been a compromise and just £200 cheaper than a Raven Tour.