If you are going to develop custom apps you should go to http://github.com/facebook/php-sdk and watch for the Facebook PHP-SDK updates so you get the latest version
Put them into the JFacebook - Distributable Client Library plugin
Publish the Plugin
JFacebook - Authentication and System Plugins
For the Authentication Plugin: Publish it, and make it's order '0'.
Publish the System Plugin
(See Note ***)JFacebook Login Module
You can override the module layouts by copying the templates in the /tmpl folder and modifying them into a 'html/mod_jfacebookloginmodule' folder of your currently selected template.
You can customize the button text, or just leave it blank