To install the Windows Live Messenger (in this example version 2009) unattended you need to do the following steps:

• Download the Windows Live Messenger (link)
• Start the installation (wlsetup-custom.exe or wlsetup-<language>.exe)Make sure you only select the Messenger and select install
• At this moment the files necessary for installing are being downloaded from Microsoft.The files are placed in the following directory :
  C:\Program Files\Common Files\Windows Live\.cache
  (or in x64 systems : C:\Program Files (x86)\Common Files\Windows Live\.cache
• In the directory 97c2eed51ca3df1 the file for Messenger is placed (messenger.msi)
• Copy this file and install it using msiexec :msiexec.exe /i Messenger.msi /qb
• Copy the files : contacts.msi, wlc.msi, RichUpload.msi, wllogin.msi, WLXSuite.msi, choiceguard.msi, messenger.msi
• Start them using a script, for example batch file :

  start /wait msiexec /i contacts.msi /qb
  start /wait msiexec /i wlc.msi /qb
  start /wait msiexec /i RichUpload.msi /qb
  start /wait msiexec /i wllogin.msi /qb
  start /wait msiexec /i WLXSuite.msi /qb
  start /wait msiexec /i choiceguard.msi /qb
  start /wait msiexec /i messenger.msi /qb

• You can also check the cache.ini. It should have something like this :

[neutral::Watson-x86::any]

Path=C:\Program Files\Common Files\Windows Live\.cache\4eef240a1ca3df1

Name=Microsoft Application Error Reporting

Hash=KfSNnRqyy+jLu4ohy2791aWK+80=

dw20shared.msi=KuGigDg6XOJnJMzWKLEvkisPROg=

[neutral::crt80::any]

Path=C:\Program Files\Common Files\Windows Live\.cache\54c86c491ca3df1

Name=Microsoft Visual Studio Runtime

Hash=xtTIjwSBidzC0aTqiLWQtslWpKA=

crt.msi=DkJQbXS5iesiW9P/fps51XTwm+8=

[neutral::Contacts-ship::ship]

Path=C:\Program Files\Common Files\Windows Live\.cache\594faf9e1ca3df1

Name=Windows Live Communications Platform

Hash=CtArq7VXhUshXealNS+a/A1hW1s=

Contacts.msi=xjz0XOEDmyPh0kFcwCWkwcJ9X2A=

[en::wlc-ship::ship]

Path=C:\Program Files\Common Files\Windows Live\.cache\5da4f5d41ca3df1

Name=Windows Live Call

Hash=kBd+hX7KeqqZNu/e4H4FBd3umAo=

wlc.msi=Nu9jYdDVlAQtxw5R7Oh7sdhFFU8=

[en::RichUpload-en::ship]

Path=C:\Program Files\Common Files\Windows Live\.cache\615139951ca3df1

Name=Windows Live Upload Tool

Hash=vYlBJ1qTNxxHNnUliP+ft8W5t00=

RichUpload.msi=uEhYas7CSIwJMM+pZr3VwoHqqaE=

[en::signin-5.0::ship]

Path=C:\Program Files\Common Files\Windows Live\.cache\65a8e12e1ca3df1

Name=Windows Live Sign-in Assistant

Hash=PrroZtVMlwcfLNoBFg8d7sPeC8E=

wllogin.msi=86k5uKx39t9iOqg7lb3q/iNeOps=

[en::WLXSuite-ship-14.0.8089.726::ship]

Path=C:\Program Files\Common Files\Windows Live\.cache\6a0c6b151ca3df1

Name=Installer

Hash=z6r/00ylPMSn43sUozZJSaCNp10=

WLXSuite.msi=ZweUaHVG0YwWkKHioTB6v4eu/o8=

[neutral::choiceguard-w3::ship]

Path=C:\Program Files\Common Files\Windows Live\.cache\6d6c7e351ca3df1

Name=Microsoft Choice Guard

Hash=BeuNqoBK7pWBhu+NwIiqzSa66Fk=

choiceguard.msi=+66YRlk/eZFPlzTxIiqsDBNG7Xc=

[en::Messenger-14.0.8089.0726-ship::ship]

Path=C:\Program Files\Common Files\Windows Live\.cache\97c2eed51ca3df1

Name=Messenger

Hash=WdWasbqIdoXhNYeppa5ah6oz5Lw=

Messenger.msi=wfeI0B2yz2jk/g0LnKFvmsrg0Mc=