yntax 
...  
output pythia8 [path_to_pythia81xx_directory]
</pre>

<p/>
For examples of MG5 process syntax, please see
<a href="http://madgraph.phys.ucl.ac.be/EXAMPLES/example_mg5.html" 
target="page">http://madgraph.phys.ucl.ac.be/EXAMPLES/example_mg5.html</a> 
or type <code>help generate</code>. If you specified the path to the 
<code>pythia81xx</code> directory in the <code>mg5_configuration</code> 
file, you do not need to enter it in the <code>output</code> command.

<p/>
If your preferred model is fou