Create a different environment for each domain, under bootstrap/start.php, and add specific file for it, under app/start folder. In your example, you could have:
bootstrap/start.php
// ...
$env = $app->detectEnvironment(array(
'production' => array('www.mysite.com'),
'development' => array('dev.mysite.com'),
));
app/start/production.php
$pathToFile = '/var/www/awesome';
$mysqlServer= '111.111.111.0';
app/start/development.php
$pathToFile = '/var/www/hackish';
$mysqlServer= '111.111.111.1';
You should not though, that if you're working with the default configuration files, the same is valid for them. You can read more on the documentation.