Found it, post #303.
Here are the steps I followed and the ones I skipped on purpose.
1, 2, 3 -> skip entirely
4, 5 -> do it
6 -> instead of removing the seatbelt, just pull it away and
7 -> do it
8 -> do it
No need to do any of the following steps, not even the pillar A cover has to be removed. For assembly, just reverse the steps. Step 8 is going to give just enough wiggle room to remove and put back the OSH backplate. Wear some gloves, I got like 5 "papercuts" from the edges of the headliner.
Let me know if it worked for you!