I found two steps to this:
1. Add a function into general-functions.php
function get_page_id($page_name){
global $wpdb;
$page_name = $wpdb->get_var(“SELECT ID FROM $wpdb->posts WHERE post_name = ‘”.$page_name.”‘”);
return $page_name;
}
2. Add this code to your header.php
echo get_post_meta(get_page_id($pagename),’header-tag’,1);
3. On the page you want to add custom header tags to, add a custom field called header-tag with your code to inject.