Starting with WildFly 8.0.0.Beta1, we create and upload an installer for MyFaces.  The installer takes advantage of WildFly's Multi-JSF feature in order to add MyFaces.

Here are the exact steps you need to follow.

1. Download the installer jar for your WildFly version from Nexus.
2. Rename the installer jar from *.jar to *.cli.  (for example, install-myfaces-2.1.12.cli)
3. Start WildFly
4. cd to <JBOSS_HOME>/bin for the running server where you want to install the new JSF.
5. Start the Command Line Interface and invoke this command then restart WildFly.

[standalone@localhost:9999 /] deploy <local path to archive>/install-myfaces-2.1.12.cli

If you want the default JSF implementation to be MyFaces 2.1.12, invoke this command then restart WildFly.

[standalone@localhost:9999 /]/subsystem=jsf/:write-attribute(name=default-jsf-impl-slot,value=myfaces-2.1.12)

If you do not want MyFaces to be the default implementation, add this to your web.xml in the MyFaces application

<context-param>
   <param-name>org.jboss.jbossfaces.JSF_CONFIG_NAME</param-name>
   <param-value>myfaces-2.1.12</param-value>
</context-param>

Notes for other JSF versions and Implementations

See Steps to add any new JSF implementation or version to WildFly and Design of WildFly Multi-JSF feature