Wie kann ich ein Daumenregister erstellen?

\documentclass[a4paper, oneside, 12pt]{scrbook} 
%Seitenzahlen mittig, keine LEERSEITEN

%\documentclass[a4paper, cleardoubleplain, oneside 12pt]{scrbook}
%Seitenzahlen rechts und links, keine LEERSEITEN

    \usepackage[T1]{fontenc}
    \usepackage[utf8]{inputenc}
    \usepackage[ngerman]{babel}
    \usepackage{scrpage2}
    \usepackage{graphicx}
    \usepackage{xcolor}
    \usepackage{blindtext}

    \makeatletter
    %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
    %  DAUMENREGISTER
    %  Chapter thumbs with scrpage2
    %

    % Safty first
    \@ifundefined{chapter}{\let\chapter\undefined
      \chapter must be defined to use chapter thumbs!}{%

    % Two new commands for the width and height of the boxes with the
    % chapter number at the thumbs (use of commands instead of lengths
    % for sparing registers)
    \newcommand*{\chapterthumbwidth}{5em} %{2em}
    \newcommand*{\chapterthumbheight}{2em} %{1em}

    % Two new commands for the colors of the box background and the
    % chapter numbers of the thumbs
    \newcommand*{\chapterthumbboxcolor}{red} %{black}
    \newcommand*{\chapterthumbtextcolor}{yellow} %{white}

    % New command to set a chapter thumb. I'm using a group at this
    % command, because I'm changing the temporary dimension \@tempdima
    \newcommand*{\putchapterthumb}{%
      \begingroup
        \Large
        % calculate the horizontal possition of the right paper border
        % (I ignore \hoffset, because I interprete \hoffset moves the page
        % at the paper e.g. if you are using cropmarks)
        \setlength{\@tempdima}{\@oddheadshift}% (internal from scrpage2)
        \setlength{\@tempdima}{-\@tempdima}%
        \addtolength{\@tempdima}{\paperwidth}%
        \addtolength{\@tempdima}{-\oddsidemargin}%
        \addtolength{\@tempdima}{-1in}%
        % putting the thumbs should not change the horizontal
        % possition
        \rlap{%
          % move to the calculated horizontal possition
          \hspace*{\@tempdima}%
          % putting the thumbs should not change the vertical
          % possition
          \vbox to 0pt{%
            % calculate the vertical possition of the thumbs (I ignore
            % \voffset for the same reasons told above)
            \setlength{\@tempdima}{\chapterthumbwidth}%
            \multiply\@tempdima by\value{chapter}%
            \addtolength{\@tempdima}{-\chapterthumbwidth}%
            \addtolength{\@tempdima}{-\baselineskip}%
            % move to the calculated vertical possition
            \vspace*{\@tempdima}%
            % put the thumbs left so the current horizontal possition
            \llap{%
              % and rotate them
              \rotatebox{90}{\colorbox{\chapterthumbboxcolor}
              {%
                  \parbox[c][\chapterthumbheight][c]{\chapterthumbwidth}{%
                    \centering
                    \textcolor{\chapterthumbtextcolor}{%
                      \strut\thechapter}\\
                  }%
                }%
              }%
            }%
            % avoid overfull \vbox messages
            \vss
          }%
        }%
      \endgroup
    }

    % New command, which works like \lohead but also puts the thumbs (you
    % cannot use \ihead with this definition but you may change this, if
    % you use more internal scrpage2 commands)
    \newcommand*{\loheadwithchapterthumbs}[2][]{%
      \lohead[\putchapterthumb#1]{\putchapterthumb#2}%
    }

    % initial use
    \loheadwithchapterthumbs{}
    \pagestyle{scrheadings}

    }
    %
    %  End of chapter thumbs with scrpage2
    %
    %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
    \makeatother

 %===========
\begin{document}
%===========

\tableofcontents

\part{Überschrift des 1. Teils}
\chapter{Kapitel 1}
\section{Abschnitt}
\subsection{Unterabschnitt}
\subsection{Unterabschnitt}
\subsubsection{Unterunterabschnitt}
\paragraph{Paragraph}
\subparagraph{Unterparagraph}

\subsection{Unterabschnitt}

\chapter{Kapitel 2}
\section{Abschnitt}
\subsection{Unterabschnitt}
\subsection{Unterabschnitt}
\subsubsection{Unterunterabschnitt}
\paragraph{Paragraph}
\subparagraph{Unterparagraph}

\chapter{Kapitel 3}
\section{Abschnitt}
\subsection{Unterabschnitt}
\subsection{Unterabschnitt}
\subsubsection{Unterunterabschnitt}
\paragraph{Paragraph}
\subparagraph{Unterparagraph}

\part{Überschrift des 2. Teils}
%===========
\end{document}
%===========