1:
2:
3:

Mittwoch
Samstag
Dienstag					

1:
2:
3:

Dienstag
Mittwoch
Samstag					

1:
2:
3:
4:
5:
6:
7:
8:
9:
10:
11:
12:
13:
14:
15:
16:
17:
18:
19:
20:
21:
22:
23:
24:

function SortDays(List: TStringList; Index1, Index2: Integer): Integer;
Const
  DayOfTheWeek: array[0..6] of String = ('montag', 'dienstag', 'mittwoch',
                                         'donnerstag', 'freitag', 'samstag', 'sonntag');

  function GetWeekDay(Day: String): Byte;
  begin
    for Result:=0 to 6 do
      if DayOfTheWeek[Result]=LowerCase(Day) then
        Break;
  end;

var i1, i2: Byte;
begin
  i1:=GetWeekDay(List[Index1]);
  i2:=GetWeekDay(List[Index2]);
  if i1<i2 then
    Result:=-1
  else
    if i2<i1 then
      Result:=1
    else
      Result:=0;
end;					

1:

stringlist.CustomSort(@SortDays);