After you climb out of Black Velvet Canyon and reach the high saddle just west of Hidden Peak, you descend into a wash. The path of least resistance should lead you into this wash well before this point, but regardless, look for it. Here, you exit the wash and head cross-country to the east and the cliffs of the Monument. The route then swings around to the northeastern side of the peak before climbing via gullies to the summit area. Cairns mark the easiest way, but any skilled route-finder should be able to manage it in any event.
Red Rock Canyon NCA, NV-- January 2013