I dont know about Dublin specifically but if you are flying CX and have Marco Polo status or one world sapphire/emerald you will have access to a lounge. There is no exception like you describe as far as I know.
Technically it says on the website for both Marco Polo and for oneworld exec club members
Lounge access is limited to lounges operated by CX/KA only.
(admittedly the website is not the most up to date thing in the world)
Anyhow I've not had anyone try to impose that at the various outstations, but as Dublin is new for cx and the lounge is run by the airport I thought I'd ask