First the Tomcat changes ( I am using Tomcat 7 but it should work the same in Tomcat 6 too). Edit server.xml file in conf directory and scroll down until you see the <Host> section there. Copy the host section and paste it again so you have two host sections and modify the name attributes to contain the two domain names. Also point appBase attributes to two different folders (create them under the Tomcat directory). You will deploy your apps to the ROOT folders under each appbase directory so that they can be accessed as http://www.domain1.com and http://www.domain2.com
workers.properties can be as simple as following two lines. Which connects to the worker w1 to ajp port of Tomcat.
worker.list=w1
worker.w1.port=8009
Now to the Apache 2 configuration. Make sure you have uncommented NameVirtualHost *:80 line in httpd.conf. Now add two <VirtualHost> sections for the two domains as below. Note that I have left out other mod_jk configuration directives.
<VirtualHost *:80>
ServerName www.domain1.com
JkMount /* w1
</VirtualHost>
<VirtualHost *:80>
ServerName www.domain2.com
JkMount /* w1
</VirtualHost>