Ember.js migration from 1.8.1 to version 2.+

We have a quite big application built on the version 1.8.1. We would like to migrate to version 2.0 or higher. We have a few guestions: - Does exist some step-by-step manual how to do it? - Can we use 2 different versions of ember in the same time? Because of continuous migration...

We would like to avoid overwriting of the whole application...