Using config files other than app.config for different configurations

[Matthew]

I have created two configurations. One is called Release-Internal and
one is called Release-External. I also have two config files named
Internal.config and External.config. The difference in the files is
that the server locations included within each file are either the
local internal addresses or the external public addresses. I've set
the "override file" property in the configuration option property page
to be Interal.config for Release-Internal and to External.config for
Release.external. The effect of that seems to be when you build a
deployment package then the correct .config file is deployed as
AppName.exe.config. My problem with that is that I often rebuild a
project without deploying a new MSI file. What I would like to have
happen is that .NET detects that since I'm building the project in
Release-External to use the External.config file to create an
AppName.exe.config file, and vice-versa. However, when building the
projects, .NET will only use App.Config. If there is no file named
App.Config it won't create any file named AppName.exe.config. How are
others getting around this?

Thanks in advance.
Matthew