Some monsters are very fast, some monsters are slow, and some monsters always go last in combat... yet there is no FG game mechanism to handle this.
In order to avoid having to redo the Monsters and Treasure module, and in recognition that C&C itself only addresses the issue with some creatures, I would suggest supporting an Effect that can be added to actors in the CT to reflect automatic modifiers to Initiative rolls. I think 3 settings should normally be sufficient: First (combatant always goes first), Last (combatant always goes last), and a modifier number which can be added/subtracted by Initiative rolls made by that actor.
Now as to the details on how this would exactly work rules-wise... not sure. But let the conversation and/or brainstorming begin.