At it stands, wading though the base code is a bit of a mess, trying to find certain key events in order to override them. I'm going to separate some of these out into another file, and call them "hooks". These will be separate small functions that can be expanded upon instead of having to override big, complex functions.
These are not events called by the engine, but instead, game events that the base code takes care of. Here's a list of some so far, please add any along the same lines you think would be good--

door_hits_party

door_hits_monster

monster_takes_damage

party_falls_down

party_climbs_up