Ok, I am sending two seats. Here are Steve's instructions:
Leave the tracks on, it helps keep the carbon from getting scratched.
To separate the backrests remove the four torx bolts , they are sealed with lock tight so use the right sized torx socket and good solid pressure. The round backrest ajuster knob can be removed by using a flat screwdriver to pry off the little round cap, then use a punch and hammer and drive the rod out. The retainer ring will be in reusable shape.
That's it, the backrest is free. I wobble it back and forth from the seat cushion while simultaneously pulling up hard. Its tight but will separate. Once it is in two peices you can use the rod and handle to readjust the tall backrest brackets down so the cushions will fit in your boxes.
Package and ship with payment included. No tax will apply. They are $1500 a peice. Let me know if your sending one or two and I'll get an invoice sent out to you right away.