How to create Layered Navigation for custom product collection?

http://stackoverflow.com/questions/17924813/how-to-create-layered-navigation-for-custom-product-collection

http://stackoverflow.com/questions/5726891/magento-layered-navigation-on-custom-product-collection

http://www.webdesign-gm.co.uk/news/web-design/magento-web-design/layered-navigation-on-home-page-or-any-cms-page-magento.php

https://www.sonassi.com/knowledge-base/magento-kb/yoast-landing-pages-module-with-layered-navigation/