Setting the microphone gain in window 7

I've searched and scoured the web interface for help setting up sound properties from code. I have multiple systems in each of several locations that are regularly used to record spoken audio through a microphone. To make sure the captured audio is clear enough, I need to be able to programmatically set things on startup, such as the microphone and speakers, to preset values. For some of these systems, I need to adjust the microphone gain.

With XP, I was able to use the AudioMixer library, however that doesn't do everything on Win7 systems that I have now. I've looked at the CoreAudioApi library for the master volume, but can't find anything that shows how to set the microphone gain, which now appears as a slider / numeric control rather than a simple checkbox. All other information I found is written in C ++, which I am starting out to be familiar with, and one of these examples left the impression that although Microphone Boost was found using IDeviceTopology, it could not be installed.

Any explicit help getting this would be greatly appreciated.