Worth checking UA from EWR direct to DUB too. They have J on that route. I don't think their ORD flights have award availability, as they're operated by EI.
AC has J on some days on the YYZ-DUB direct during the summer this year. Not sure if they're releasing it for rewards though. Haven't looked for it.
Finally, it's possible via the call centre to book EI flights using BA Avios.
http://thepointsguy.com/2012/04/usin...el-surcharges/