Lazaro, I think the simplest way of doing this would be to write your own eZ publish module. Once you have the module you get the permission system for free. The module would simply read the html pages and outputs them in a template. You can e.g. use an iframe if you want to include them in the same page, or you could just terminate the eZ publish processing once the html page is served.
you can set the pagelayout you want to have for the module by defining the following then you return the module result:
$Result['pagelayout'] = 'my_nice_pagelayout.tpl';
The template for pagelayout must not be under your module. It needs to be in templates/my_nice_pagelayout.tpl. This can be put in a design extension if you like.
You can have a look at the code for kernel/layout/set.php, this does change the pagelayout file.
