12.04: How to add local details to dnsmasq config

[Paul Smith]

Hi all.  So, the new integrated dnsmasq / DNS service for Ubuntu 12.04
is nice.  However it only works with NetworkManager enabled software
solutions.

I have a 3rd party VPN tool which is most decidedly NOT integrated with
Network Manager, and I need to add appropriate extra setup to the
dnsmasq configuration to handle the DNS forwarding for that environment.
I used to manage all this myself by hand so I'm quite aware of what
needs to be done and how it all works.

However, I don't know how to add extra content to the dnsmasq
configuration network-manager uses.  I can see that network-manager
starts a dnsmasq server that listens on 127.0.0.1 (good stuff) and that
the configuration file is /var/run/nm-dns-dnsmasq.conf which I assume is
being auto-generated by network manager.

That's all good stuff, BUT I need a way to add my own set of
configuration to that nm-dns-dnsmasq.conf file, preferably dynamically
(so I can script the bring-up and bring-down of my proprietary VPN and
get it added and removed at the appropriate times).

How can I add/remove config from the local DNS configuration?