There is of course a numbering scheme for Chess960 (Fischer Random Chess).
I invented it some years ago, and it is widely accepted. For details see
e.g. in my (German) book on Chess960
http://www.chessbox.de/Compu/fullchess1_e.html or see at the two page
document I gave (first page with table) to the Chess Tigers
http://www.chesstigers.de/download/chess960_regeln.pdf .
With best regards, Reinhard Scharnagl.