\RequirePackage{graphicx}
\let\IncludeGraphics\includegraphics
\graphicspath{{images/}}
\documentclass[10pt]{article}
\usepackage[T1]{fontenc}
\usepackage{lmodern}
\usepackage{pstricks}
\usepackage{pstricks-add}
\usepackage[spanish]{babel}
\usepackage{microtype}% sólo pdftex
\begin{document}
Example code
\begin{verbatim}
\documentclass[10pt]{article}
\usepackage[T1]{fontenc}
\usepackage{lmodern}
\usepackage{pstricks}
\usepackage{pstricks-add}
\usepackage[spanish]{babel}
\usepackage{microtype}% sólo pdflatex
\begin{document}
\begin{pspicture}[showgrid=true](4,2)
\psscaleboxto(8,2){Hola}
\end{pspicture}
\begin{pspicture}[showgrid=true](4,2)
\psscaleboxto(4,2){foo bar}
\end{pspicture}
\end{document}
\end{verbatim}
Obtain
 \IncludeGraphics[scale=1]{test-tmp-0.pdf}
and
\IncludeGraphics[scale=1]{test-tmp-1.pdf}
\end{document}