While doing a search after maurice added the links above, here is probably the best bet yet. Might try to do away with the gearing.
Here is a link to the youtube video, shows how to construct as well as model in flight:
https://www.youtube.com/watch?v=3TKl0TJSYgo
Now for some screen shots:
Here is the connection of the two wires;
Here is photo of wire connection in relation to wing mounts:
Here is the gearbox:
Now thinking the gearbox might be the reason why this works: No tension on the wires so they can flex and rotate without wearing through a bearing/guide surface.
If I hook rubber band directly to the wire shafts, it will tend to pull it with force. and cut through a guide tube like what this designer used to angle it towards the engine mount once leaving the fuselage.
Boy this is going to take some studying. I've messed around with gear drives when I did the wind turbines several years ago. Made mine out of cardstock pulleys using o-ring rubber to create drive belts. Still have several plastic gear cogs that I could use as well.
Now thinking a 3D printer could help with a gear box...
Mike