Multiple instance in tomcat

I need to install a tomcat6 with multiple instances like instance1,instance2 and instance3 in a server.

I came to know that for that we need to install tomcat6,apache2.0,mod_jk1.2 and jre with tools.jar installed.And we need to create multiple instances with same web.xml and difference server.xml for each instance.I didn't get the mod_jk1.2 bin file.

Can anyone please instruct the step by step procedure to install multiple instances of tomcat in a server?