Having done it and a few variations, here is the deal.
It is a long day, and requires a car shuffle (one car parked at Buller, one at Sheepyard), and this is a looong car shuffle.
On the bikes, descend via route of choice from Buller (when I did it last best descent was Corn Hill 4WD track) to the Howqua Gap. However, with all the new XC trail work going on, maybe there is a better descent to the Gap now??
Descend the Circuit Track south for maybe a couple of kms, and turn right onto the Corn Hill Logging Rd . Descend this to Pikes Flat (a few small climbs).
From just after Pikes, you are after the High Track walking track, which literally follows the Howqua all the way past Richies Hut to about 4 Mile Creek (just shy of Sheepyard Flat). This is without a doubt a sensational bit of almost all gradually descending fun flowy singletrack. 10+ km at least as the crow flys, but much windier.
Ensure you get some maps (25000 series maps are Buller, Magdala and Timbertop). Bring spare bike bits (derailleur and chain breaker) and food. It can be a long day, especially with a larger group. Recommend car shuffling the night before. We have enjoyed it most by camping at Sheepyard or one of the 6/8 mile spots, car shuffling, then riding the next day. Nothing like finishing the ride literally into camp, with an esky full of beer (and maybe the fire going..)
PS just realized that my avatar is me on Klingsporn.........
