I have a simple input file contains PSTricks code as follows.
% sample.tex
\documentclass[cmyk]{minimal}
\usepackage{pstricks}
\usepackage[paperwidth=144bp,paperheight=108bp,margin=0bp]{geometry}
\parindent=0bp
\begin{document}
\begin{pspicture}(\paperwidth,\paperheight)
\psframe[linecolor=red](\paperwidth,\paperheight)
\end{pspicture}
\end{document}
It is compiled using:
latex -interaction=nonstopmode %1
dvips -R -t unknown %1
ps2pdf -dAutoRotatePages#/None -dCompatibilityLevel#1.5 -dPDFSETTINGS#/prepress %1.ps
pdftops -level3 -eps %1.pdf %1-temp.eps
epstool --copy --bbox %1-temp.eps %1.eps
Before invoking the epstool, my sample-temp.eps contains the following:
%!PS-Adobe-3.0 EPSF-3.0
% Produced by xpdf/pdftops 3.02pl4
%%Creator: dvips(k) 5.99 Copyright 2010 Radical Eye Software
%%Title: sample.dvi
%%LanguageLevel: 2
%%DocumentSuppliedResources: (atend)
%%BoundingBox: 0 0 144 108
%%EndComments
%%BeginProlog
%%BeginResource: procset xpdf 3.02pl4 0
%%Copyright: Copyright 1996-2007 Glyph & Cog, LLC
Note: I don't understand why the second row does not exist in Herbert's EPS.
I failed to execute epstool because the second row has a single % that should be %%. The following screenshot shows the error log.

Based on Lev's comment, I tried to add -level3 switch to pdftops, but it still does not solve the problem. I don't understand what sed in Lev's comment, what is that?
This is my pdftops version:

-leve3is nonsense, nearly all printers do not have this level installed – Jul 12 '11 at 06:12xpdflib, don't know if there is a version withpopplerfor Windows. – Jul 12 '11 at 06:24pdftoepsto produce postscript for later conversion to a different format, most often because they are integrating with a postscript-based journal publisher workflow, that will later be distilled to PDF for distribution. Anyway, my comment here was in relation to usingsedto fix the missing%. – Lev Bishop Jul 12 '11 at 13:50sedis a tool to automate editing text files. See for example the manual page. Thesedprogram2s/^/%/means "add a%at the beginning of the second line". (The-level3is not important for your current problem but it can produce very much smaller .eps files under some circumstances.) – Lev Bishop Jul 13 '11 at 19:40