Adding some details to avoid "words confusion":
at time of Vbox 3.x there was 2 virtualbox related dkms packages:
- one to build the vboxdrv modules, necessary on host
to run a virtualbox machine
- the dkms-vboxadditions, which provide support when running PClinuxOS as guest
Now I don't remember the details, other then when trying to upgrading the kernel to 2.6.38.x the dkms module build failed, therefore I delayed the kernel upgrade until I decided to install VirtualBox 4.x.
The getvirtualbox script, actually get and install the virtualbox software, including the vboxdrv dkms module. All fine.
When a user decide to install the guest-additions, they are available to the guest machine, as mounted ISO image, is up to the guest user to install the guest additions, not a difficult task however.
this should be the Texstar's post you are referring to:http://www.pclinuxos.com/forum/index.php/topic,90702.msg760459.html#msg760459
the depreciated modules are the guest-additions, still I do not see any problem with the current "getvirtualbox" package behavior.
If, for some reason which is beyond me, instead of the "getvirtualbox" Texstar will decide to provide the a VirtualBox as packages instead of as script,
that's will require the dkms-vboxdrv package, still the dkms-guest additions could be not provided (after all they are going to be installed on the guest OS).
The best thing you can do is to get in touch with Texstar directly, about the future directions.