I've been trying to justify this description with Google satellite and street views, and think I'm close, but have a question or two and one suggested improvement.
> Follow the path and before an underpass of the highway (the road continues towards Irache), turn left. The road borders the highway for about 500 mtrs. Turn left into the oak forest again. The Camino meanders through the forest for about 2.5 km and ends on a large sand track.
I see this underpass, and a dirt road curving into the woods. However, from satellite view I only see it connecting to a long series of switchbacks going up the mountain. I don't question that the Camino is hidden in the forest, and the posts indicate that it is well marked. I'm guessing that it "roughly" parallels the route of A-12, and perhaps skirts some of the smaller tilled fields I see from above. I'm guessing this large sand track is one off NA-1110 that crosses under the A-12.
> Turn left and follow this track for about 2km without deviating either left or right.
This is perhaps the most frustrating bit. If I search for "Camino Luquin", I find many similar images showing a lovely landscape of a dirt road winding and climbing among varying fields, and I couldn't match it up with what I saw in satellite view.
Wait - I just worked it out . . . must have been a seasonal thing. Satellite view is plowed fields in the spring, while all the photos are high summer. These photos all show pretty much the same view, and I noticed two other roads angling off to the right. Combined with slight turns in the Camino just before and after these roads, I'm now able to place this location.
> After a heavy ascent and at a T-junction, enter a narrow path straight ahead.
I was initially confused over justifying a T-junction with the notion of going straight ahead. However, I think I've sorted it out by zooming in on satellite view. The road you were on ends at a T, and if you turn left, the narrow track bears off to the right ~10 meters beyond this? This runs parallel to the dirt road for perhaps 300 meters.
> This leads eventually towards a larger sand track and leads into Luquín.
The track widens where two tracks join it from above on the left. You're now on Calle San Martin.
> After the Luquín church at your right and a bar on the left, continue straight down along an asphalted road until a path off to the right. Follow this until a main road, turn left, cross and after 120 mtrs turn right into a meandering footpath which leads to a sand track, bordering the highway. Turn left until an underpass (300 mtrs.), cross underneath and after 150 mtrs connect with the Camino from Monjardín to Los Arcos (turn left)
This "path" actually starts as a concrete road, and soon turns to dirt at the edge of town. What isn't mentioned is that about 500 meters from the start of this road, your suggested route bears right on a double-rut lane, which in turn brings you to NA-1110.
What I'd suggest, is instead of turning off on this lane, you continue on the dirt road for about a km. After a minor zig-zag, you come to two large agri-business structures right ahead of you. Bear right on a similar road just before these, which will soon cross NA-1110 to a wider road, and then bring you directly to the underpass. No walking on asphalt, or along highways.
Here's my initial take on it. I drew a straight line in the woods where I couldn't follow the Camino. You can set the Map to satellite view in the top right corner.
http://ridewithgps.com/routes/6893527
Charles