Well.. I had a style conflict with my previous solution. So I gave up using a highlighted version, but just an XML text (with correct tab indentations of course!). I also needed to put a frame outside my xml document, and got this I found a nice Latex package called "fancyvrb". With a simple "frame" attribute, it works great.. Hope it helps!..
\begin{figure}[htbp]
\begin{Verbatim}[frame=single]
<task id="..." performer="..." type="...">
<name>...</name>
<description>...</description>
<params>
<param type="..." name="..." datatype="..."/>
.
.
</params>
</task>
\end{Verbatim}
% \vskip
\label{fig:spec_task}
\end{figure}
\begin{figure}[htbp]
\begin{Verbatim}[frame=single]
<task id="..." performer="..." type="...">
<name>...</name>
<description>...</description>
<params>
<param type="..." name="..." datatype="..."/>
.
.
</params>
</task>
\end{Verbatim}
% \vskip
\label{fig:spec_task}
\end{figure}