There's nothing to configure. SSO will automatically use a cache instance based on the configuration of the default cache of the "web" cache container.
For me that configuration not work.
I have app01 deployed on Server-group-01 and app02 deployed on Server-group-02 both on full-ha profile.
When i logged on app01 and go to app02, logged is required again. This application works well on Jboss AS 7 with SSO.