Ionic 4 additional scripts

I am trying out ionic 4 for my next project. I had some custom scripts which I would run in ionic 3.

ionic 3 package.json:

"scripts": {
    "minify": "ionic-app-scripts minify",
    "clean": "ionic-app-scripts clean",
    "build": "ionic-app-scripts build",
    "lint": "ionic-app-scripts lint",
    "ionic:build": "ionic-app-scripts build",
    "ionic:serve": "ionic-app-scripts serve"
  },

the first 2 were loaded from a custom config file.

I am not able to figure out how to do this in ionic 4 as I only see these entries:

"scripts": {
    "ng": "ng",
    "start": "ng serve",
    "build": "ng build",
    "test": "ng test",
    "lint": "ng lint",
    "e2e": "ng e2e"
  },

Thanks.