On the topo map, these trails look to be separate and happen to join up for a short stretch. This isn't the case however - there's no obvious turns or junctions and that 'short cut' (the most direct route from each end) doesn't actually seem to exist!

Entering on the Duck Hole end is easy: there's a signpost and gate on McCarrs Creek Road, just before the bridge over the creek of the same name. From the road you can cycle round the gate and a small bush to the left. If you're heading up McCarrs Creek Road from Church point don't take the first firetrail off to the left - that's not signposted and is actually the Chiltern Track.

The other end becomes Terrey Hills trail and is again signposted. However, that is only at the end of a short sealed road that seems to have no name and runs from the main road (McCarrs Creek again). It's pretty much the driveway for house numbers 301 & 303 so watch out for those and turn there. This driveway is perhaps 200m and is quiet a steep drop from the main road:

It's a nice ride through forest so is pretty shady. I don't recall any particularly challenging hills but there were a few undulations along the way. Think this is about 4.7kms in total but someone please correct me.

It's not far (about 1600m) to the Terrey Hills Perimeter Track at the West end. From the East you could cycle up to Centre Track (2Km away) or down into Bayview/Church Point on the road.