Ok so you copied ATA3.driver into C: of the Emergency-Disk.
Have you started the driver in the Startup-Sequence of the disk? If you haven't there is no way of Setup to know the existence of the Secondary channel.
You must put:
C:ATA3.driver QUIET
as the first line in Emergency-Disk's Startup-Sequence
You might even have to run ATA3.prefs in order to save the new settings but I don't think it's essential.
I used Secondary channel for setting 3.9 and 4.0 but MorphOS for PUP isn't starting (due to FastATA compatibility issue) so I putted it back to Primary as slave and works in triple OS's.
