composeWith1.js

// generator from another package
this.composeWith('backbone:route', {
  options: options
}, {
  local: require.resolve('generator-bootstrap')
});

// local subgenerator
this.composeWith('mygenerator:git', {
  options: options
}, {
  local: require.resolve('../git')
});

composeWith2-easily.js

this.easily
  .setResolver(require.resolve)
  .composeWithExternal(
    'generator-bootstrap',
    'backbone:route',
    options
  )
  .composeWithLocal(
    'git',
    'mygenerator:git',
    options
  );