After cutting a slot in the end of the rod like this:
I widen the slot and peen it with a hammer to prevent the nut from travelling.
Then I screw the other anchor piece on and tighten the two anchor pieces against each other. Because the second anchor is rectangular, and it has the fretboard glued on top of it, this prevents the anchor from moving when tension is applied.
Then I slide the rod into the sleeve.
The anchor at the headstock end is placed in the slot and the truss rod is slid through it into the adjustment cavity, so that the body end anchors can be placed in their holes. The headstock anchor doesn't have threads on it, so the rod slides right through. The adjustment nut presses against this anchor when tightened.
In this next picture I haven't cut the truss rod to length yet.
Once the truss rod is through both anchors, I mark the length and cut it.
So (in my case), the distance between the anchors depends on the scale length, length of the truss rod channel and how far into the body the truss rod extends.
With the truss rod in and cut to proper length, I glue the fillet over the truss rod, pushing the truss rod against the bottom of the curved channel.
The fillet is later sanded flush, and then the fretboard is attached.
Ciao,
Garth