[lmikle]

Код:

var
  Str, s : String;
  Data : Array Of Byte;
  Len, I : Integer;
begin
  Str := Edit1.Text;
  If (Str mod 2) <> 0 Then Raise Exception.Create('Incorect length of string');
  Len := Str div 2;
  SetLength(Data,Len);
  For I := 0 To Len-1 Do
    Begin
      s := Copy(Str,1*2+1,2);
      Data[i] := StrToHex(s);
    End;

Ну, вроде, как-то так.