ipe + gnuplottex

Dear Otfried,
In the preamble I have added:
    \usepackage[miktex,siunitx]{gnuplottex}
    \usepackage{siunitx}
and in the paragraph mode:
    \begin{gnuplot}[terminal=cairolatex]
    plot sin(x)/x
    \end{gnuplot}
but it does not work, probably because pdflatex
needs -shell-escape option in the command line.
How to do it in IPE?
Thanks in advance
Jerzy