This is what I meant by "scripting hooks". I have something like the following in package.json for various projects:

  "devDependencies": {
    "bower": ">=1.3"
  },
  "scripts": {
    "postinstall": "bower install"
  }

This way I never need a global install of bower, nor do I ever really need to use it directly. I don't see why something similar couldn't be set up for any other npm-able package manager or build tool. A bit of googling seems to indicate that npm can update node using e.g. the "n" module. That module or another like it can of course be a dependency in package.json.