hi. there is this package in AUR http://aur.archlinux.org/packages.php?ID=14621 called virtualbox_bin_additions
but it is severely broken - it uses sudo to mount an iso on a loopback device - it does not create a vboxadd user needed for the vboxadd service and there already are 2 packages in [community] for additions virtualbox-additions and virtualbox-ose-additions (with virtualbox-ose-additions-modules) so i think it could better be deleted.
