The dirt section of the famous Mulholland Drive is an 8.19 mile fire road stretch located between the Canyonback Road trailhead and Topanga Canyon Road. It can be easily done one way or another, and there are signs at the major intersections. Just take the fire road from one end to the other. It is pretty well trafficked by hikers and mountain bike riders, and offers nice views of the valley and the canyons going down towards Malibu. Make sure to go to the top of the tower at the former Nike missile radar control site at some point after your FKT attempt for the best views.
Well done Allison!