Here is the link to .zip of a sample project for using Camera control of XLabs. It's named XPA_PickMedia_XLabs_XFP.
XPA stands for 'Cross Platform App' and XFP stands for 'Xamarin Forms PCL'. In my app I set links to the needed files in this project so that any changes in it are automatically taken account for.
I have tested this in Android (Galaxy Note 4) and Windows Phone (Lumia 830). I have not tested it in iOS 8 as I am yet to have a paid account and my iOS simulators are not loading apps. If someone can test it in iOS, I will be very thankful.
I have written some notes in the CameraViewModel.cs on how to use it.
Please let me know if you have any comments, concerns or improvements.