ok, meant to update this a few days ago, but other issues have taken priority (health related, not car related, lol - and no, not covid)
anyway, i can confirm the boot DOES just snap in from below the plastic surround... I did not even have to pull that trim off.. just angled the bottom of the boot down into the hole, lined it all up and gently pulled up on the fabric around the edges, and "snap" she just popped into place!! yay!