This set of instructions and code will help you to set up username authentication for your SilverStripe website. Note that the SilverStripe CMS has typically relied on E-Mail authentication, so this could cause problems if developers have assumed email authentication. I've provided a patch and information for issues I've found so far.
These are instructions for setting up bounce handling for SilverStripe, and assumes you use cPanel for site managment. You should be able to mirror these steps accross to other systems also.
Finally, I got around to properly coding my log in widget to use a SilverStripe login form, rather than a hack form that submits to the Security controller.
I came up with a hack way to add flv videos to SilverStripe page content.