Though this seems to be an old question with many answers I'm posting another one, because it provides information about another approaches (looking more convenient than already mentioned), and the question itself remains actual.
First, there is a blogpost Running multiple versions of Google Chrome on Windows. It describes a method which works, but has 2 drawbacks:
Second method is a preferred one, which I'm currently using. It relies on portable versions of Chrome, which become available for every stable release at the portableapps.com.
The only requirement of this method is that existing Chrome version should not run during installation of a next version. Of course, each version must be installed in a separate directory. This way, after installation, you can run Chromes of different versions in parallel. Of course, there is a drawback in this method as well: