Hi Michael,
Thanks for your message.
Unfortunately,it may be difficult to find place of birth for Andrew as most Catholic records are still held locally so it will be difficult to find any records pertaining to him without knowing what parish they were recorded in.
There are some places where you can search online, however it may be difficult to discern whether the results are relevant to your family or not without more information:
www.familysearch.org has a huge database of genealogical records including some church records for Ireland.
www.rootsireland.ie have a large collection of Irish Church records, however you have to pay to use this site.
I did a search for Mackasey in the Tithe Applotment Books. These are land records that were recorded 1823-38. There were no results. However 7 results were returned for McCasey, 3 of which were in Co. Carlow:
http://titheapplotmentbooks.nationalarchives.ie/search/tab/results.jsp?surname=McCasey&firstname=&county=&parish=&townland=&search=Search
As there is no genealogical information given in these records however it is impossible to know whether they are relevant or not-however they may give you a starting point if all else fails.
It is important to remember the different variations in spelling for the surname. Here are some:
http://www.irishtimes.com/ancestor/surname/index.cfm?fuseaction=Go.&UserID=
Do you have any documentation pertaining to the family that mentions any place names in Carlow at all? This can include wills, marriage/death records,census records, letters, diary entries etc. SOmetimes a parish name may even be found on a tombstone.
Here are some other websites that you may find useful.
The National Archives of Ireland http://www.nationalarchives.ie/genealogy1/genealogy-records/introduction/
The National Library of Ireland http://www.nli.ie/en/family-history-introduction.aspx
The National Archives UK ? genealogy search: http://www.nationalarchives.gov.uk/records/looking-for-person/
The Public Records Office of Northern Ireland http://www.proni.gov.uk/index/family_history.htm
Irish Times: http://www.irishtimes.com/ancestor/index.htm
Irish Genealogy Tool kit: http://www.irish-genealogy-toolkit.com/
From Ireland: www.from-ireland.net
Genealogy Links: http://www.genealogylinks.net/uk/ireland/carlow/index.html
Sorry not to be of more help.
Kind regards,
Genealogy Support