There are a lot of tips and hints out there on the internet, which describe how you could add support for Java Server Faces and Facelets to the Eclipse environment.
Mostly, they deal with adding code completion for JSF/Facelets tags and so on. There are some possibilities to achieve this, ranging from creating TLD files to using the JSP editor in Eclipse for the XHTML code of the Facelets pages.
But the “trick” I prefer is much more simple
You want to see it? Well, just download and install the JBoss Tools and you have it all!