This is a template for BeardLib to add new music into the game.
You will need the mod BeardLib Music Module Addon for the module to load from your main.xml
You will need at least BeardLib version 2.5.
https://modworkshop.net/mydownloads.php?action=view_down&did=18107
For Custom Music to work you need to have it in a bink video http://www.radgametools.com/down/Bink/RADTools.exe
And for heist tracks it will have to be split up for events.

Video guide for the template by NarratingFox

Some info: Music module can be heist only, menu only or both!
As of revision #3 you don't have to put AddFiles anymore and instead the module will create it for you using the sources
Default assets directory is 'Assets' but it can be changed by the value 'assets_directory' in the music module, example:

<Music id="knock_knock" source="music/knock_knock/assault" menu="true" assets_directory="Assets" />

Heist+Menu Music:

<Music id="knock_knock" source="music/knock_knock/assault" menu="true" heist="true"> 
    <event name="setup" source="music/knock_knock/setup"/>
    <event name="anticipation" source="music/knock_knock/anticipation"/>
    <event name="assault" source="music/knock_knock/assault"/>
    <event name="control" source="music/knock_knock/control"/>
</Music>

Heist only Music

<Music id="knock_knock" source="music/knock_knock/assault" heist="true"> 
    <event name="setup" source="music/knock_knock/setup"/>
    <event name="anticipation" source="music/knock_knock/anticipation"/>
    <event name="assault" source="music/knock_knock/assault"/>
    <event name="control" source="music/knock_knock/control"/>
</Music>

Menu only Music(the events are only for heist tracks)

<Music id="knock_knock" source="music/knock_knock/assault" menu="true" />   

Thanks Ellie for the music track and helping to test.