Successful downclimb of Haleakala on May 29-30, 2009. From Paliku the trail was a bit overgrown but followable on the descent. It's fairly well marked in the confusing areas. One should be prepared for the descent, but it's not nearly as steep/scary as the NP would have you believe.
Finding the lower trailhead to drop a shuttle vehicle is probably the crux. The road is just east of the Kaupo Store. One lane, it looks like it was once paved, but is in the process of being absorbed by the jungle. Drive carefully as this road is still in use. Drive upwards to the signed trailhead at about 1mi, 1040' elevation.