On a Downloaded Build

The easiest way to do this is by editing my Example Event script, extract the files inside mods/custom_events/

On the Source Code

Adding it to Chart Editor

1. Open ChartingState.hx and around Line 50 you will see the eventStuff array.

2. Add your new Event's name and description to it.

Coding your event

1. Open PlayState.hx

2. Search for the function named triggerEventNote, add a new case using your event's name and code your event's action there.

Early Trigger

Some events like "Kill Henchmen" are triggered earlier than their chart position (280ms earlier). If you want to do something similar, search for the function eventNoteEarlyTrigger and set a new case with your event's name and how many milliseconds earlier should it be triggered.