I don't know how to help you install Sony's Library Software, but I can recommend a much better alternative,
calibre. It will do most everything Sony's Library does, and much more. You can't use it to buy books from the Sony store though, but you get a better selection (and better prices) from
Fictionwise and
BooksOnBoard anyway. They sell LIT books, and the DRM from those can be removed in 20 seconds with ConvertLIT.