Uwe,
part of your spell no work for me.
I must deleted "\protect\numberline{}"
With this the entire ERT appears in my output.
I use \addcontentsline {toc}{chapter}{Preface}. It�s work ok.
But Preface appears in columm of chapter numbers, (extreme left).
textclass scrbook no available in my lyx.
I have:
#LyX 1.3 created this file. For more info see http://www.lyx.org/
\lyxformat 221
\textclass book
\begin_preamble
\usepackage[latin1]{inputenc}
\usepackage{babel}
\date{}
\end_preamble
\language spanish
\inputencoding latin1
\fontscheme default
\graphics default
\paperfontsize 11
\spacing single
\papersize b5paper
\paperpackage a4
\use_geometry 0
\use_amsmath 0
\use_natbib 0
\use_numerical_citations 0
\paperorientation portrait
\leftmargin 2.3cm
\topmargin 2cm
\rightmargin 2cm
\bottommargin 1.8cm
\secnumdepth 3
\tocdepth 3
\paragraph_separation indent
\defskip medskip
\quotes_language french
\quotes_times 2
\papercolumns 1
\papersides 2
\paperpagestyle plain
\bullet 0
0
7
-1
\end_bullet
\layout Title
La tecnolog�a en la Antig�edad
\newline
Un estudio comparado
\layout Author
Marcelo Victorio Acu�a
\layout Chapter*
\shape italic
Pr�logo
\begin_inset ERT
status Open
\layout Standard
\backslash
addcontentsline{toc}{chapter}{
\backslash
protect
\backslash
numberline{}Pr�logo}
\end_inset
\layout Standard
\noindent
my text ...
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