Installing a Strong name signed assembly into the Windows GAC using MSI

Simple Steps:

1. Create a setup project.
2. Right click on the installer project and go to view the File System
3. Right click in the left pane and add Global Assembly Cache "special folder"
4. Click on the GAC folder and add the assembly or project output (make sure all is strong named otherwise the installer will fail).

Custom Actions and properties like TARGETDIR

If you want to pass an MSI property to your custom action exe, this is how you do it:

CustomAction -> Arguments: "[TARGETDIR]\".

Don't forget the trailing \

For Windows Installer properties such as [TARGETDIR] that return a directory, in addition to the brackets you must include quotation marks and a trailing backslash

If you forget, you'll spend 2 hours debugging an almost un-debuggable problem.