How to route speaker output and mic input to a dummy device on Android

Question

I want to route speaker output to dummy device1, and route mic input to a dummy device2 on Android, so that reading from device1 gets the audio stream from all Android apps and phone calls, and writing to device2 generates fake audio input for all Android apps (skype etc). Are these possible?

My phone is Samsung Galaxy Note II, and there is an audio_policy.conf file under /etc. It contains the following codes:

global_configuration {
  attached_output_devices AUDIO_DEVICE_OUT_EARPIECE|AUDIO_DEVICE_OUT_SPEAKER
  default_output_device AUDIO_DEVICE_OUT_SPEAKER
  attached_input_devices AUDIO_DEVICE_IN_BUILTIN_MIC|AUDIO_DEVICE_IN_BACK_MIC
}

Is this the right location that I replace the built-in audio interface with my dummy file? And how to make Android accept my dummy file?

Thanks!