Actually, AA uses Sabre (I believe...), and a bunch of other OW airlines use Amadeus. You should be able to view--and in some cases edit--Amadeus-ticketed segments on finnair.com.

I've always called AA to get my Amadeus record locator. However, I did just find this thread which states that you can use ba.com to translate your AA PNR to an Amadeus number: http://www.flyertalk.com/forum/ameri...itinerary.html