.sequelizerc

var path = require('path')

module.exports = {
  'config':          path.resolve('server', 'config', 'database.json'),
  'migrations-path': path.resolve('server', 'migrations'),
  'models-path':     path.resolve('server', 'models'),
  'seeders-path':    path.resolve('server', 'seeders'),
}

index.js

'use strict'

import fs from 'fs'
import path from 'path'
import Sequelize from 'sequelize'

var basename = path.basename(module.filename)
var env = process.env.NODE_ENV || 'development'
var config = require(path.join(__dirname, '/../config/database.json'))[env]
var db = {}
var sequelize

if (config.use_env_variable) {
  sequelize = new Sequelize(process.env[config.use_env_variable]);
} else {
  sequelize = new Sequelize(config.database, config.username, config.password, config);
}

fs
  .readdirSync(__dirname)
  .filter((file) => {
    return (file.indexOf('.') !== 0) && (file !== basename) && (file.slice(-3) === '.js');
  })
  .forEach((file) => {
    var model = sequelize['import'](path.join(__dirname, file));
    db[model.name] = model
  })

Object.keys(db).forEach((modelName) => {
  if (db[modelName].associate) {
    db[modelName].associate(db)
  }
})

db.sequelize = sequelize
db.Sequelize = Sequelize

export default db

I wasn't following this thread! Thanks for answering!

didn't find another example of .sequelizerc, thank you very much