Zend certified PHP/Magento developer

Replace template inside the email template

I have an module to send email out, it was using default translational email header and footer template. I don’t want to change the header in the Content->Design->Configuration.
Only for this module, I want to use another header and footer that I created in the email template

{{template config_path="design/email/header_template"}}

in app/design/ I can hardcode and overwrite it, but what is the syntax to point to the new template I just created? (inside Marketing-> Email Template)
(for example my new template name: new_template_header)