To invoke the login dialog, you need to include the file https://static.miniclipcdn.com/js/mc.js, which is accessible over both http and https:

<script type="text/javascript" src="//static.miniclipcdn.com/js/mc.js"></script>

Once this script is included, you then need to initialise the API with your app ID. For example:

MC.init({
	app_id : "YOUR_ID_HERE",
	language_code : 'en' // optional, defaults to 'en'
});