That's not a massively helpful looking installation manual!
The bottom one is obviously looking for a signal from the ignition switch, but it doesn't tell you what signal that is exactly! (switched ignition live? starter motor?)
Similarly the "engine cut-off".
What exactly does it want here? Something going from +ve to -ve or vice-versa?
Mechanically injected diesels definitely had a signal for engine shut off (the only way to stop the engine was to cut fuel by a solenoid valve, which went from +ve valve open to -ve valve closed by spring).
Modern diesels do it by just stopping fuel injection and (all) petrol engines do it by just stopping ignition. So there isn't a signal as such, it would just lose the switched ignition live?
Nearest thing on a prelude that I can think of would be a the fuel shut-off solenoid in the event of an accident, which on 4th gens I think is fitted to JDM but not UKDM? Not sure about 5th gens?
Or could pick up the electric fuel pump signal???
Is there any other info in the manual?