Oracle 11g XE does not run natively on Mac OS X. However, you can have it setup running on a VM and have your natively-running JBoss servers connect to it via port-forwarding (along with additional steps below):

• Install EAP 6.x on Mac OS X
• Install RHEL 7.x as a VM using Virtual Box
• Install Oracle 11g XE on RHEL 7.x
• Create DB users on Oracle DB server
• Add port forwarding for Oracle DB’s default ‘1521’
• Turn off firewall on RHEL 7 and disable SELinux. Presumably, you don’t need such lockdown features when running locally. If needed, grant appropriate firewall permissions for ip/port. Otherwise, you can permanently disable the firewall service:

  service firewalld stop
  chkconfig firewalld off