Save slider as a stand-alone page, Wordpress plugin, Joomla module; embed in page with Insert-to-Page Wizard; publish to server via built-in FTP client.
what that says is that you can save it as a stand alone page, a wordpress plugin or a joomla module.
it does not say that it is only for wordpress or joomla.
if you save it as a stand alone page you would then take only the required code from that page and place it in the overall_header.html file of your phpbb style.
you do NOT need the standard html page code like <head> </head>, meta tags, etc.
you do NOT need the <body> or </body> tags either.