DO you have KOTN installed ?? -- the boots from it have a script that makes woodland creatures not attack you while wearing them - so if you wanted the effect without wearing the boots you could easily add that script to another item in the CS.
Those boots don't use an universal method, so to speak. Knights of the Nine directly edits some creatures adding them to a new Predator faction, and the player is also added to that faction when wearing the boots and removed when not.
With Wrye Bash, you could change the aggression or confidence stats of the creatures you want to alter in an esp, then add a Actors.AIData tag to that file, and import it into the bashed patch to maintain compatibility with other mods changing those creatures. But you still have to edit any new creature added by mods directly yourself.
So yes, you have to make patches over OOO and MMM for the new creatures they add, and preferably use Wrye Bash to preserve the changes from the passive wildlife mods you use when using those mods.