In order to have Notes databases use II2LN-functionality, you must either install II2LN on the Notes client -or- on the Domino server. Note that server installation require a server-license.
Normally you will use the setup application to install II2LN. However, sometimes you will need to validate an install, for example if you have multiple Notes clients on a single workstation, or if you for some other reason suspect an erroneous installation. Please see here for a detailed list of the contents in the installer.
The setup application for II2LN will attempt to detect all your installed Notes clients and/or Domino servers. During installation you will clearly see which Notes and/or Domino versions II2LN attemt to install on.
In the screen shot above, you see that II2LN plan to install II2LN support for the found Lotus Notes rel. 6 installation. If you have multiple Notes versions, you can select yourself which versions you install II2LN support for.
The installer will show you a confirmation dialog before anything is installed or modified:
The most important aspect of the installation, is to place the files of II2LN in a directory that is referenced by the PATH environment variable on your machine. Otherwise LotusScript won't find the VCII2LN.DLL and it's two run time DLLs during execution.