Yes, that's definitely possible, assuming that you're using JSF 2.0, part of Java EE 6.
As to the managed beans and other JSF classes like validators, converters, etc, just annotate them with @ManagedBean, @FacesValidator, @FacesConverter, etc and package them in the JAR the usual way. You only need to provide a JSF 2.0 compatible /META-INF/faces-config.xml file in the JAR.
<?xml version="1.0" encoding="UTF-8"?>
<faces-config
xmlns="http://java.sun.com/xml/ns/javaee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-facesconfig_2_0.xsd"
version="2.0">
</faces-config>
This way JSF will be triggered to scan the classes in the JAR for JSF specific annotations. Alternatively you can also just register them in the JAR's faces-config.xml the JSF 1.x way.
As to Facelets resources, just drop them in /META-INF/resources folder of the JAR. It'll be treated the same way as public webcontent of the WAR.
See also: