It seems that if one wishes to use a different container than the 'hibernate' one it still ends up using the hibernate container.  (AS 7.2.0.Final-redhat-8)
For example if we create a new container called 'jpa' as below and verify the cache container started up fine via logs/admin console.
 
           <cache-container name="jpa" default-cache="local-query" start="EAGER" module="org.jboss.as.jpa.hibernate:4" jndi-name="java:jboss/infinispan/jpa">  
                <local-cache name="entity">  
                    <transaction mode="NON_XA"/>  
                    <eviction strategy="LRU" max-entries="10000"/>  
                    <expiration lifespan="1800000"/>  
                </local-cache>  
                <local-cache name="local-query">  
                    <transaction mode="NONE"/>  
                    <eviction strategy="LRU" max-entries="10000"/>  
                    <expiration max-idle="1000000"/>  
                </local-cache>  
                <local-cache name="timestamps">  
                    <transaction mode="NONE"/>  
                    <eviction strategy="NONE"/>  
                </local-cache>  
            </cache-container>  
  
and add the cachemanager reference in persistence.xml for 2LC 
 
     <property name="hibernate.cache.infinispan.cachemanager" value="java:jboss/infinispan/jpa" />  
     <property name="hibernate.cache.region.factory_class" value="org.jboss.as.jpa.hibernate4.infinispan.InfinispanRegionFactory" />  
 
 but it still uses the hibernate container. 
 
INFO [org.jboss.as.clustering.infinispan] (ServerService Thread Pool -- 59) JBAS010281: Started example.war#com.example.blah cache from hibernate container