OK. So, I've got my wife's 9.9J N3ds in hand.
In the mail, a Sky3ds+, Gateway, and my 8.1J.
I'll downgrade the wife's to 9.2. Do Oot/CN (sky3ds) on there to get into GW and save.
On mine, boot into GW from Sky3ds. Follow the update steps in the manual.
From there, I'll have GW mode, and...