\documentclass[a4paper,oneside,12pt]{book}
\usepackage{vruler} % to have a vertical graduation
\usepackage{txfonts}
\usepackage[english2,tight]{minitoc}
\begin{document}
\setvruler[1cm][0][10][3][0][0pt][0pt][0pt][] % with vruler package
\doparttoc
\faketableofcontents
\part{First part}
\parttoc
\chapter{First chapter of first part}
\chapter{Second chapter of first part}
\part{Second part}
\renewcommand{\mtcgapbeforeheads}{100pt}
\renewcommand{\mtcgapafterheads}{80pt}
\parttoc
\chapter{First chapter of second part}
\chapter{Second chapter of second part}
\part{Third part}
\renewcommand{\mtcgapbeforeheads}{20pt}
\renewcommand{\mtcgapafterheads}{10pt}
\parttoc
\chapter{First chapter of third part}
\chapter{Second chapter of third part}
\end{document}
