I found various bits of information on the internet which conflicted, so I struggled, no information on the internet was absolutely conclusive, my advice is to hope
someone local will confirm.
Anyway, there's a website for the current church - the St. James Church of Ireland, Donemana - this is the webpage covering a brief history:
http://stjamesdonagheady.wordpress.com/a-short-history-of-the-parish/ Also on that website are contact details for the Church, you may wish to contact them directly to clarify the historical locations.
The brief history seems to suggest three churches, the oldest at "Church Hill" since the early 1600s, a "St. Michael's" from the late 1700s, and St. James from 1879.
If you google
33 Longland Road, Donemana and look at the google maps "hit", you will easily find St. James, the current church.
Head up that road about 150 yards (in a NE direction) and you will see a little loop of road south of the Longland Road. If you switch from "map view" to "satellite view" or "streetview" you will just about see what are gravestones / ruins - I wonder is this St. Michael's?
Turning to the OSI 6" mapping series of 1837 - 1842, here is a church in the townland of Bunowen which fits the ruins / graves I previously mentioned lying about 150 yards NE of the current St. James Church:
http://maps.osi.ie/publicviewer/#V1,644974,903672,6,7This website allows you to pan, zoom in/out and view on a more contemporary map, so play around. Obviously the St. James church hadn't been built at that stage, though it looks, comparing old and modern maps, as if it was built in land surrounding Earls Gift - I'm lead to believe from internet references, St. James is also called Earls Gift (Earlsgift)?
Going back to the original (early 1600s) church at Church Hill, I'm wondering if a reference in the OSI 6" mapping series of 1837 - 1842 to "Ruins of Old Church" just south of the townland of Church Hill is the oldest church? If you pan a bit north from my previous link you will see it, otherwise follow this link:
http://maps.osi.ie/publicviewer/#V1,645356,904465,6,7