build.cake

private void InstallOpenCoverFromLocalPackage() 
{
    var settings = new NuGetInstallSettings 
    {
        //Source = new[] { @"..\Tools\LocalPackages\" },
        Source = new[] { @"C:\Some\FullPath\Tools\LocalPackages" },
        
        OutputDirectory = "tools"
    };

    NuGetInstall("OpenCover", settings);
    //NuGetInstall("OpenCover.nupkg", settings);
}