VS 2005: 

Use setup.exe included in the ActiveWriter download to start installation. During setup, you will be asked to install DSL Tools redistributables from Microsoft along with ActiveWriter, if you don't have it already installed. ActiveWriter heavily depends on DSL Tools and cannot run without it.

Other than that, there are no quirks to mention about the installation.

What is installed?

To the selected installation folder:

• Altinoren.ActiveWriter.Dsl.dll (The core. Registered to the GAC)
• Altinoren.ActiveWriter.DslPackage.dll (VS Package components. Registered to the GAC)
• EULA.rtf
• Readme.htm

Under your VS installation

• \Xml\Schemas\ActiveWriterSchema.xsd
• \Common7\IDE\ItemTemplates\CSharp\1033\ActiveWriter.zip (Visual Studio templates to create blank .actiw files)
• \Common7\IDE\ItemTemplates\VisualBasic\1033\ActiveWriter.zip