Apache has their own support for virtual domains. This is the only program I recommend using the internal virtual domain mechanism. When you run something through inetd there is a cost. The program now has to start up each time you run it. That means slower response times which is unacceptable for web service. Apache also has a mechanism for stopping connections when too many come in.
However, if you did want to run Apache through inetd then add the following line to your inetd.conf file:
www stream tcp nowait www /usr/bin/virtuald virtuald /virtual/conf.www httpd -f /var/www/conf/httpd.conf
In the /var/www/conf/httpd.conf file you have to specify:
ServerType inetd
Then configure each instance of the Apache server like you would normally for single domain use.
At the time of this writing there is no virtual web HOWTO. However, I am under the impression one is coming. Eventually I will just refer to that HOWTO and have some notes on it. If it does not come soon and I get enough requests I will write a small section on how to configure the Apache virthost directive.