installmsse.ps1

if  (!(test-path "HKLM:\Software\Microsoft\Windows NT\CurrentVersion\AppCompatFlags\Layers")) {
    New-Item -Path "HKLM:\Software\Microsoft\Windows NT\CurrentVersion\AppCompatFlags\Layers" -force -ErrorAction SilentlyContinue
}

new-ItemProperty -Path "HKLM:\Software\Microsoft\Windows NT\CurrentVersion\AppCompatFlags\Layers" -Name "C:\Windows\Temp\mseinstall.exe" -Value "~ WIN7RTM" -force -ErrorAction SilentlyContinue

#Write-host "Installing MSSE..."
if (Test-Path 'C:/Windows/Temp/mseinstall.exe'){
    start-process -FilePath 'C:/Windows/Temp/mseinstall.exe' -ArgumentList '/s /q /o /runwgacheck /disableoslimit' -wait
} else {
  Write-output "MSSE binary not found"
  exit 1
}

if (get-service MsMpSvc) {
    write-output "Microsoft Security Essentials Installed"
} else {
    write-error "MSSE failed to install!!"
    error 1
}