The registration must be done via Techstream, my handbook merely mentions the fact two sets can be registered, for when swapping summer/winter wheels.
"It is not necessary to register the ID codes when replacing normal tires with snow tires, if
the ID codes for the wheels of both normal tires and snow tires are registered beforehand."
It directs one to contact the dealership to perform the registration and change-over.
Lexus tech doc is the only place I found with info on the 'three press' process
This is the doc in question, obviously directed at my model and year, so may not be relevant to others.
Tyre Pressure ID Registration.pdf