Tab Through to Dynamic Message Template Fields

I'd love to have to have the ability to tab through/to fields we need to upate with each email in message templates. Like custom fields that a user can open an email, insert the template, and then tab through to insert the data pertinent to that email. We were able to use this function in Postbox, and it's a gamechanger for people using lots of template language that needs to be customized for each recipient.