\input utf8-t1 % conversion from UTF-8 to T1 by encTeX
\documentclass{book}
\usepackage[papersize={,80mm},topmargin=5mm,
    botmargin,strictheight,
    leftmargin=0mm,flap=40mm,textwidth=50mm,spine=8mm,
    cropmarks,cropframe,croptitle=Cover]{zwpagelayout}
\usepackage[T1]{fontenc}
\usepackage{lmodern,rotating}
\pagestyle{empty}
\parindent 0mm
\def\thePageNumber{Designed by Zdeněk Wagner}
\begin{document}
\small
\hbox to \textwidth{%
  \vbox to \textheight{\hsize \CropFlap \centering
        Back flap\vfill}\hss
  \vbox to \textheight{\hsize \UserWidth \centering
        Back cover\vfill \leavevmode ISBN+EAN}\hss
  \vbox to \textheight{\hsize \CropSpine \centering
        \vfill
        \begin{sideways}Spine\end{sideways}\vfill}\hss
  \vbox to \textheight{\hsize \UserWidth \centering
        Front cover\vfill \LaTeX}\hss
  \vbox to \textheight{\hsize \CropFlap \centering
        Front flap\vfill}}
\end{document}