How setup Varnish, Nginx and Apache and APC?

How setup Varnish, Nginx and Apache and APC?

On Ubuntu 13.04 I've installed Varnish, Nginx, Apache and APC. It's one
server with one IP address using php-fpm.
I was able to successfully set it up to do CloudFlare > Varnish > Nginx >
Wordpress/APC for domains on the server.
However some domains on the same server I want to be able to serve using
CloudFlare > Varnish > Nginx Reverse Proxy > Apache > WordPress/APC.
While I know how to do one or the other, I'm unsure concept wise how I
would be able to do both at the same time.
Presumably, Varnish would listen on port 80 for all domains. But then some
domains such as example1.com and example2.com would need to use just
nginx. While other domains such as example3.com and example4.com would
need to use nginx reverse proxy and pushed to Apache.
On StackOverflow people noted this should be possible, but now posting
here to get help with how to actually do it on Ubuntu. Most importantly
the theory aka which ports each server should be listening for and such.
If there is actually no way to do this easily with one IP but would be
possible with two IP's on one server I'd be open to hearing how that would
work instead?