How to change lang code in the URL

Hello ...  I am looking for a way to customize the format of the language code in the URL ..,

Instead of http://<server>/en-US/<page name>

I want  http://<server>/en_US/<page name>

The below knowledge base seemed to show promise - except  its basically blank

www.sitefinity.com/.../how-to-change-the-languagecode-in-the-sitefintiy-urls