If you are running VirtualBox with Linux guest under a Linux host, you will definitely need symbolic links at one point in time. And, while you can do links toward shared folders, you cannot create a link on shared folder itself. You will get something like:
ln -s /something /somethingelse
ln: failed to create symbolic link '/somethingElse': Read-only file system
Well, fortunately it's easy to enable connection on per share basis. Just run the following command on your host (replacing GuestName and ShareName with correct information):
VBoxManage setextradata 'GuestName' VBoxInternal2/SharedFoldersEnableSymlinksCreate/ShareName 1
If your machine is running, you will need to fully shut it down (no, restart doesn't help) and you get to enjoy the full symbolic link glory.