Manual installation would require the installation of the NPanday repository which can be downloaded from the NPanday site (click the Repository link and accept the license agreement).
PATH=%PATH%;C:\Program Files\Microsoft Visual Studio 9.0\Common7\IDE;C:\WINDOWS\Microsoft.NET\Framework\v3.5; C:\WINDOWS\Microsoft.NET\Framework\v2.0.50727;C:\Program Files\Microsoft Visual Studio 9\SDK\v3.5\bin; C:\Program Files\Microsoft Visual Studio 8\SDK\v2.0\bin;C:\Program Files\NUnit 2.4.3\bin
mvn npanday.plugin:maven-vsinstaller-plugin:[version]:install
Note: Close the Visual Studio Integrated Development Environment (IDE) before installing maven-vsinstaller-plugin.
C:\Documents and Settings\[user_home]\My Documents\Visual Studio 2005\Addins\NPanday.VisualStudio.AddIn