If you're using Xamarin, I found a guide on their official forum explaining how to do this:
- Download the package from the internet. There are many sources for this, one possible source is the CyanogenMod web site.
- Start up the Android Player and unlock it.
- Drag and drop the zip file that you downloaded onto the Android Player.
- Restart the Android Player.
Hereafter, you might also need to update the Google Play Services from the Google Play Store.
Hope this helps for anyone else who has troubles finding the documentation.