[O] Latex code inbetween beamer frames

[Giacomo M]

Dear all,
I would like to set a background image for some slides. AFAIK, the way 
to achieve this in beamer is by using sth like:
\usebackgroundtemplate{\tikz\node 
{\includegraphics[width=\textwidth]{mybackpic}};}
before the \begin{frame} of the slide of interest (and after the 
\end{frame}).
I would like to be able to do this in org-mode, and couldn't find a 
solution so far.
Any suggestion would be really appreciated.

Thanks,

Giacomo