When I've used mod_proxy with apache, I've used the following in my conf file (foo.com running on 8001):
LoadModule proxy_module lib/apache/libproxy.so
AddModule mod_proxy.c
<VirtualHost *>
ServerName www.foo.com
ServerAlias *.foo.com
ServerAlias *foo.com
Options Indexes Includes FollowSymLinks MultiViews
ProxyPass / http://127.0.0.1:8001/
ProxyPassReverse / http://127.0.0.1:8001/
CustomLog /var/log/httpd/foo_log combined
</VirtualHost>