$WIM = "C:\dism\install.wim"
$ServerName = "Windows Server 2012 R2 SERVERSTANDARD"
$Updates = "C:\dism\MSU"
dism /mount-wim /wimfile:$WIM /mountdir:C:\Mount /name:$ServerName
foreach ($file in Get-ChildItem $Updates -Recurse -File)
{
    if (($file.Extension -eq ".cab") -or ($file.Extension -eq ".msu")) 
    {
        $file.FullName
        DISM /image:C:\Mount /add-package /packagepath:$($file.FullName)
    }
}
Dism /unmount-wim /mountdir:C:\Mount /commit