Not sure exactly what you want to control but you could set Remote Management in your MM to on and allow Share Screen. THen on your MBA you click on "Share Screen" in the finder Window when you see your MM in the left window. Then you should see your MM Desktop on your MBA. You can control anything then?
If you want to control the music and play it on your MBA then use Shared Library.
Also you might want to look at AirPlay in the AirPort Express possibly. This allows control of sound, as opposed to iTunes.
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