Deploy UWP apps to Windows 10 Mobile

Deploy.cs

// Initializes MultiTargetingConnectivity with current PC culture
var connectivity = new MultiTargetingConnectivity(Thread.CurrentThread.CurrentUICulture.LCID);
var devices = connectivity.GetConnectableDevices();

// Gets the first physical device attached to PC.
// WARNING: if more than a single device is connected to the PC deploy will fail.
var phone = devices.FirstOrDefault(x => !x.IsEmulator());

// PhoneProductId of the app, you can find it in your Package.appxmanifest
var package = Guid.Parse("XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX");
var device = phone.Connect(true);

try
{
    // If application is already installed simply uninstall it.
    if (device.IsApplicationInstalled(package))
    {
        device.GetApplication(package).Uninstall();
    }
}
catch { }
try
{
    // Installs the app to the device.
    // Parameters are:
    // Guid productId = PhoneProductId
    // Guid instanceId = PhoneProductId
    // string applicationGenre = "32", that means "Sideload"
    // string iconPath = "2" if the package extension is "appx"
    // string xapPackage = absolute path of the package
    var app = device.InstallApplication(package, package, "32", "2", full_path_to_the_file);
}
finally
{
    // Disconnect to the current device.
    // IMPORTANT: call this method or you have to reboot the phone to apply changes.
    device.Disconnect();
}

Full explanation at my blog here: https://frayxrulez.wordpress.com/2015/06/18/how-to-sideload-uwp-apps-to-windows-10-mobile/