I've decided to remove this option.
The next version will be fully compatible with Vista in a non-administrator mode (except of the setup process). In this mode it is not possible to copy files to Program Files.
The other reason is that I don't think that it was really useful and I now think that it better to let the user explicitly manage his set of libraries.
BTW, when you open a project Basic4ppc now checks whether there are more updated (comparing the file's creation date) libraries in the 'libraries' folder than the libraries in the project folder and updates the local libraries if required.