// it's really complex, and there are many ways to do it.

// first way
// first use the command: haxelib install polymod

// add this to the project.xml: <haxelib name="polymod"/>

import polymod.Polymod;

// initialize mods

Polymod.init({
  modRoot:"modspath/",
  dirs:["mods"]
 });
 
// all if not most file loader's backends will load things correctly

// second way, much harder.

// do it yourself with a custom file loading system using multiple packages:
import openfl.display.FileSystem;
import sys.io.File;
import openfl.display.BitmapData;
import openfl.media.Sound;
// all these packages negate the manifest and are perfect for softcoded loading