I came this way last night to inspect. I have twigged what he was referring to.
If you go along Glendevon, you go under the (old) railway bridge and arrive in golf club car park. To your right is an informal dirt track that skirts the golf course (probably used by the greenkeepers' vehicles). Affixed to the lamp post is one of the "Police Notice" signs saying "do not cycle on the pavement". It's not a pavement so I'm not sure what it's doing there.
If you want to get on to the railway path here, you have to go left, past the golf clubhouse and then left again will take you onto the path. Currently there's a large bollard saying "path closed" in direction of Balgreen. It's open in direction of Corstorphine, although path isn't surfaced for first few hundred metres.
My usual approach to the Corstorphine Path is back streets from Roseburn Park (the H2EP route)