Automate config of Firefox and Opera proxy on Android

We have a little app on Android that requires us to configure the proxy server and port of the FireFox and Opera mobile browsers. We would like to automate this process, rather than have the user do this manually. You need to deliver code that does the configuration automatically. To demo the code, you probably should provide a little app. This app could have two buttons: one to configure firefox, one to configure opera. It might be not be possible to do this without user involvement. For example, the code might launch the browser and pre-populate the proxy settings. That would be acceptable.