How to pass variables to the html email layout, not the view

I have some settings variables defined in my beforeFilter in AppController that I can access in layouts as needed. These settings include dynamic content/values set by users of a CMS framework I built on top of CakePHP. These variables don’t seem to be accessible in email layouts (Template > Layout > Email > html > default.ctp). I know you can send viewVars to email templates, but how might I send variables from my controller to the email layout? These variables are needed to dynamically set the header logo and footer legal copy of the email layout. I don’t want to have to code the headers and footers into every email template, as there will be many.

Any help would be greatly appreciated. Thanks!