Threading on a ballscrew direct drive lathe (Ikegai A20)

So I'll be taking delivery of a new-to-me Ikegai A20 lathe in a couple of months and something has me very confused - threading operations. To start - the lathe doesn't have a clutch, it's direct drive star / delta operation for forward and reverse. And of course having a stationary ballscrew (instead of a turning leadscrew) means there is no threading dial. So, I figured the operators manual would sort me out - and here's what it says:

After selecting the thread pitch, the threading should be done in the following order of procedure:

1. Start the spindle in the forward direction with the motor control lever.
2. Engage the threading lever.
3. Thereafter, the carriage is reciprocated by switching the motor control lever to forward and reverse.

Click to expand...

If I am turning a thread to a shoulder, do I literally get right to the shoulder, and then simply jam the motor into reverse? Surely this wouldn't be very accurate, and the geartrain in the apron would introduce play as it reverses. Perhaps I actually need to disengage the threading lever at the shoulder (as if it were a half-nut), and then reverse the carriage to the start? But without a threading dial, does this assume a single-dog clutch in the apron? The manual doesn't talk about disengaging the thread lever?...

What am I missing? Anybody used an Ikegai before, or have a ballscrew lathe that can fill me in on the specifics?

If you want to thread right up to a shoulder,seems like it must be done reversewise......IE...away from the shoulder,and even then ,returning the tool would need some care......Can the entire ballnut unit be disengaged from the saddle(or whatever)?.....Maybe you need one of the "BANG" tool retractors ,I know my old CriDan uses this system ,and the tool retracts within a few thou each time at 1500rpm,even leaving a small exactly formed divot at the thread/shoulder interface.

Ikegai A20 vs Mori Seiki MR2000

some threading info on there