Für das übliche Bündel an Headerzeilen:

Im Setup des Extension-Templates:

page.shortcutIcon = fileadmin/img/favicon.ico

page.meta {
  robots = index,follow
  resource-type = document
  keywords.field = keywords
  keywords.ifEmpty = {$keywords}
  description.field = description
  description.ifEmpty = {$description}
}

page.headerData.5 = TEXT
page.headerData.5.field = title
page.headerData.5.wrap = <title>|: {$titlesuffix}</title>

page.headerData.10 = TEXT
page.headerData.10.value (
  <meta http-equiv="Content-Language" content="de" />
  <meta http-equiv="Content-Script-Type" content="text/javascript" />
  <meta http-equiv="Content-Style-Type" content="text/css" />
)

page.headerData.20 = TEXT
page.headerData.20.value (
  <!--[if IE 6]><link rel="stylesheet" href="{$templatepath}/css/style_ie6.css" type="text/css" media="screen" /><![endif]-->
  <!--[if IE 7]><link rel="stylesheet" href="{$templatepath}/css/style_ie7.css" type="text/css" media="screen" /><![endif]-->
  <!--[if IE 8]><link rel="stylesheet" href="{$templatepath}/css/style_ie8.css" type="text/css" media="screen" /><![endif]-->
  <!--[if IE]><link rel="stylesheet" href="{$templatepath}/css/style_ie.css" type="text/css" media="screen" /><![endif]-->
)

Und im zentralen Template in den Constants:

templatepath = fileadmin/tpl_sdfgh
keywords = Website, Snippet, Beispiel
description = Meine Beschreibung
titlesuffix = Titelanhang