They are below Alto del Perdon and because of this make sure it is not dark when you descend. I liked choosing my steps to avoid loose rocks on that descent.
An alternative, at any time of the day is this:
Having crested Alto del Perdon and admired the silhouettes, then:
1) turn right down the hill for about 2 km;
2) towards the bottom turn left (on the slip road) onto the NA-1110; or
2a) continue down on the bridge and around in a semi-circle to pass under the bridge;
3) about 1 km on, at a well formed and signed intersection, turn left on to the NA-6016
** (ignore pilgrim signage, unless you want to go Punta la Reina at this time)
4) a very short way on, see the sign to Uterga (ignore motorway details);
5) keeping to the left (facing oncoming) pass under the motorway;
6) at another roundabout follow the sign to Uterga, now less than 3 km away.
The total for this alternative is about 6 km.
The direct walkers route, from Alto del Perdon, loose rocks and all, is about 4 km
Either way one drops from about 800 m asl at Alto del Perdon to 500 m asl at Uterga. By road, the drop is quite gentle and no loose rocks are encountered.
Kia kaha (take care, be strong)