After extracting natives jboss-eap-native-6.0.0.ER3-....zip there is following message after startup:
"WARN [org.jboss.as.messaging] (MSC service thread 1-1) JBAS011600: AIO wasn't located on this platform, it will fall back to using pure Java NIO. If your platform is Linux, install LibAIO to enable the AIO journal"
I would expect, that after extracting of natives, AIO will be used automatically.
It is possible to setup java.library.path through JAVA_OPTS - but first it must be found from boot.log what current value is and then extend it. That means it is not possible update existing one.