Nagios3 and Tomcat6 configuration under Apache2.2

[Paolo Santarsiero]

Hi, I  have a Tomcat6 cluster under Apache2.2. I'd like to monitor the
system and so I want to use nagios3 but I don't know how configure
VirtualHosts for Tomcat and Nagios under Apache ( I use Ubuntu so I have
/etc/apache2/ports.conf and /etc/apache2/sites-enabled/000-default). I hope
you can help me.