I installed it by downloading virtualbox-4.3_4.3.18-96516~Ubuntu~raring_amd64.deb from virtualbox.org. I also have the extension pack installed. I've been running VirtualBox from there (obviously different versions) for several years. The video driver from nVidia works a little better, though I do keep 3D disabled for my VM because if I have 3D enabled with the nVidia driver iTunes will not let me into the store (and other 'odd' behavior). But since this is about Nouveau I won't side-track you with more details on that :-)
I installed it by downloading virtualbox- 4.3_4.3. 18-96516~ Ubuntu~ raring_ amd64.deb from virtualbox.org. I also have the extension pack installed. I've been running VirtualBox from there (obviously different versions) for several years. The video driver from nVidia works a little better, though I do keep 3D disabled for my VM because if I have 3D enabled with the nVidia driver iTunes will not let me into the store (and other 'odd' behavior). But since this is about Nouveau I won't side-track you with more details on that :-)