www.domain.com & domain.com - don't work

Could you not just use the .htaccess lines such as these to force a www. or force without? I uncommented the second set of lines to remove the www., personally.

# Various rewrite rules.
<IfModule mod_rewrite.c>
  RewriteEngine on

  # If your site can be accessed both with and without the prefix www. you
  # can use one of the following settings to force user to use only one option:
  #
  # If you want the site to be accessed WITH the www. only, adapt and
  # uncomment the following:
  # RewriteCond %{HTTP_HOST} ^example\.com$ [NC]
  # RewriteRule .* http://www.example.com/ [L,R=301]
  #
  # If you want the site to be accessed only WITHOUT the www. prefix, adapt
  # and uncomment the following:
  # RewriteCond %{HTTP_HOST} ^www\.example\.com$ [NC]
  # RewriteRule .* http://example.com/ [L,R=301]
</IfModule>

Downgrading from critical to normal, as there's a workaround.