Delphi-Quellcode:
function XlsCol(col : integer) : String;
begin
Assert (col>0,'Col must be > 0 ');
result :='';
repeat
result := chr (65 + (col - 1) mod 26]+result;
col := (col - 1) div 26;
until col=0;
end;
So gehts für alle Integer, glaube ich zumindest.