Put in "assets/mod_overrides". If there's no "mod_overrides" folder just make one. Requires BLT and BeardLib.
Thought it'd be pretty cool to combine 2 things I love.
Adds Crystalline Chill and Veiled in Black from FFXV as selectable soundtracks (Crystalline Chill ment as menu track, Veiled in Black ment as heist track). Veiled in Black uses the original and the Niflheim version, Careening into Danger and Imperial Infiltration to form the heist track.