You can replace the standard module settings page with a custom one:
1. Add necessary controller and widget classes
2. Return the URL to the custom settings page in your module's Main.php file as follows:
PHP Code:
public static function getSettingsForm()
{
return \XLite\Core\Converter::buildURL('YOUR_PAGE_TARGET', '', [], \XLite::getAdminScript());
}
Another solution is creating your custom FormField classes that display your custom HTML code.