radiotables in LaTeX-document: export numbers from orgtbl with commas as decimal separators instead of periods; with MWE and lisp-code

[AW <alexander.willand@t-online.de>]

Dear all,

I'd like to use radiotables inside a LaTeX-document. Here is a minimal working 
example:

-----------------------------------------------------------
\documentclass[pagesize, ngerman, fontsize=12pt]{scrartcl}
\usepackage[T1]{fontenc}\usepackage[utf8]{inputenc}
\usepackage{babel, comment, array, booktabs}


\title{Sicherheitsbestellung}
\subtitle{gag}
\begin{document}
\maketitle

\begin{tabular}{p{0.25\linewidth}p{0.5\linewidth}}%\toprule
  Bezeichnung & Betrag \\
% BEGIN RECEIVE ORGTBL Kaufpreis
Kaufpreis & 100000.00 \\
Darlehen & -5000.00 \\
Summe & 95000.00 \\
% END RECEIVE ORGTBL Kaufpreis
\bottomrule
\end{tabular}
\begin{comment}
#+ORGTBL: SEND Kaufpreis orgtbl-to-latex :splice t :skip 0
| Kaufpreis | 100000.00 |
| Darlehen  |  -5000.00 |
| Summe     |  95000.00 |
#+TBLFM: @3$2=@1$2+@2$2;%.2f

\end{comment}
\end{document}
-----------------------------------------------------------

I would like to have the LaTeX table with commas as decimal separators instead 
of periods, e.g.: 

»Kaufpreis & 100000,00\\« or even better 
»Kaufpreis & 100\,000,00\\«. 

To avoid misunderstandigs: The change of all periods to commas should take 
place when the org-table is »transfered« to the LaTeX table, not earlier!

I found a suggestion by Carsten Dominik here: 
http://permalink.gmane.org/gmane.emacs.orgmode/42000

-----------------------------------------------------------
(add-hook 'org-export-preprocess-hook
	  'org-use-comma-in-exported-tables)

(defun org-use-comma-in-exported-tables ()
  (goto-char (point-min))
  (while (re-search-forward "\\([0-9]\\)\\.\\([0-9]\\)" nil t)
    (org-if-unprotected
     (when (save-match-data (org-at-table-p))
       (replace-match "\\1,\\2" t nil)))))
-----------------------------------------------------------

I put that into my .emacs, restarted Emacs, but no result.
I'm using Emacs 23.3 and Org-mode version 7.8.02. Please bear in mind that I'm 
may have made strange mistake, because I do neither have experience with 
radiotables nor understand lisp.

Any help would be appreciated, thanks in advance.

Kind regards,

Alexander