If you are sure that httpd Virtual Hosting is working properly (e.g.you can request the proper, say, index.html given a sub-domain), then getting Tomcat to work should not be terribly hard.
Can you confirm that VH is working in httpd? Yes, VH's are working fine. We have a number of proxypass/reverse, rewrite among other statements in vhost files. These all have worked fine for a number of years.
