[eluser]Colin Williams[/eluser]
One way is to use theme subfolders in your view directory:
Code:
application/
views/
greentheme/
bluetheme/
You will then have a setting or config item for the theme to be used, and you need to use it when loading your views.
Code:
$this->load->view(config_item('theme_dir') .'header', $header_data);
$this->load->view(config_item('theme_dir') .'page', $page_data);