I believe the Catholic Parish records are on Ancestry
and are available on microfilm at the National Library in Dublin. The Latter Day Saints - you should be able to go to their website www.familysearch.org
and look for the location of a History Center near you. I believe at the top of the page. You then phone and make sure they have the film numbers
you want and if so no problem but they may have to order.
You can also try the same website but scroll down on the main page till you get to UK/Ireland, click on this and on the
page you go to scroll down again to Irish records. I have had no luck with this website since they upgraded it and can't find where they have put things.
There is always the Irish History Foundation but a pay website but they have collected all their material locally and each county genealogy office would of borrowed parish registers to make up their data base.
RC actual Parish registers I believe are in local custody in Ireland.
If any of the above isn't correct, hopefully someone can come along and set it straight. I live in Canada so basically only know a few websites to find information.