The following example shows how to add OEM Charset translation to daADO.pas:

function TdaChildADOQuery.Translate(Src, Dest: PChar; ToOem: Boolean): Integer;
begin
  if (Src <> nil) then
  begin
    if ToOem then
      CharToOemBuff(Src, Dest, StrLen(Src)+1) else
    OemToCharBuff(Src, Dest, StrLen(Src)+1);
    Result:=StrLen(Dest);
  end else
  Result:=0;
end;