I wrote the Irish Embassy in Beijing as to what I needed to marry a Chinese national legitimately in the eyes of the Irish government.
This is their reply :-
You will need to apply for a Certificat de Coutume from the Consular Section of the Department of Foreign Affairs, you can read more about the application process on http://www.dfa.ie/home/index.aspx?id=274
Once you have received your certificate, you should get a translation and take this with the certificate to the Chinese Embassy in Dublin for their stamp.
Kind regards,
Embassy of Ireland
3 Ritan Dong Lu
Chaoyang District
Beijing 100600 The current wait seems to be about 6 months for this, so plan ahead!!