With Slideshow2 everything went well. Download the package, edit the file like specified and voilá you've got an vertical thumbnail list. Life can be so easy...
... until you add additional pictures: With more thumbnails than the complete height of the container (around eight in my case) the problems reveal. There is no scrolling!
After some (read alot) try and error I wrote to the googlegroup of the developer and sent a complete error description and a way to reproduce the problem in. So stay tuned :-)