\documentclass[12pt]{article}

\usepackage{moreverb,plain,graphicx}
\def\verbatimtabsize{4\relax}
\def\listingoffset{1em}
\def\listinglabel#1{\llap{\tiny\it\the#1}\hskip\listingoffset\relax}
\def\mylisting#1{{\fontsize{10}{11}\selectfont\listinginput[1]{1}{#1}}}
\def\myoutput#1{{\fontsize{10}{11}\selectfont\verbatimtabinput{#1}}}

\begin{document}

\end{document}