$objShell = New-Object -ComObject ("WScript.Shell")
$objShortCut = $objShell.CreateShortcut($env:USERPROFILE + "Start Menu\Programs\Startup" + "\program.lnk")
$objShortCut.TargetPath("path to program")
$objShortCut.Save()
this will create link from scratch.
[тут могла быть ваша реклама] http://www.sysadmins.lv