Moving a Network from non-www to www

First I appologize because I know some of this has been posted already but can someone give me a clear step-by-step process for changing a WordPress Multisite install that is using the Domain Mapping Plugin and currently has a base domain of wpms.example.com to a multisite that would be using a http://www.wpms.example.com base domain.

So, I need to move it from non-www to a default www. The end goal is to have our non-www redirect to a www domain for every website in our mulitisite install.

I have read about two options:

1. Changing the wp-config.php to say:

define( ‘MULTISITE’, true );

define( ‘SUBDOMAIN_INSTALL’, true );

$base = ‘/’;

define( ‘DOMAIN_CURRENT_SITE’, ‘www.example.com’ );

define( ‘PATH_CURRENT_SITE’, ‘/’ );

define( ‘SITE_ID_CURRENT_SITE’, 1 );

define( ‘BLOG_ID_CURRENT_SITE’, 1 );

And 2. Possible adding a .htaccess file that repoints the non-www to the www.

The problem, I’m being told by my team, is that both of these create a redirect loop.

I look forward to hearing a response and thank you for taking the time to answer this.