hi bro, there r so many ways to sterilise the rocks - all the above mentioned.
For my aptasia i use a pointed knife, when u lift the rock up usually the polyp will danggle, take the knife, cut off as much as u can, then with the pointed knife (or a wire sometimes), carve into its burrow n scrape.
Make sure u clean the ap off the rock cus its quite sticky.
Happy reefing
but u cant boil ur zoe n sps, right?