Marking this solved is helpful for other users so they know I am not working on the project, and in my opinion it can not be done. But if someone finds a solution, I would appreciate them sharing it with me.

Using the virtualbox package alone in the debian repository will not work. Additional software must be downloaded from the origional source. In fact, debian 8 and 9 have a complete download from the origional source. Eariler debian versions have a small download to suppliment the debian package.

I do not understand installing kernel headers in the host.

The cd does not support debian guest.

Please consider reading my post. I mentioned the VirtualBox Debian repositories which may work better than using VirtualBox from the Debian repositories.
I deliberately typed a step-by-step example of how I would do it (and some bits I have done) because your posts seemed to be a mix of doing things on the guest and host but not necessarily doing the right thing on the right one.
As to kernel headers on the host as I recall if they're not installed VirtualBox drivers aren't built properly but it is a long time since I installed VirtualBox so I may be wrong -- it's still worth installing them anyhow as it won't do any harm.

After some testing it would appear that pedros is correct -- there is something happening with Debian 6 meaning that the guest additions won't install. In fact, they won't even run on my Debian 6 guest.

Thank you 273, LQ Addict, for trying. Here are my old notes. According to them, guest additions will install on Debian 6, and winxp guest will run in the virtualbox. Please try to run any debian guest in the virtualbox.

posted 2012 08 21. squeeze 6.0.3.
virtualbox. result of no guest additions.
virtualbox-warning
failed to access the usb subsystem.
could not load the host usb proxy service
(verr_file_not_found).

virtualbox.txt 2012 08 20.
1. INSTALL VIRTUALBOX ONTO DEBIAN.
debian> select file,
/home/r/virtualbox-4.1_4.1.18-78361-debian-squeeze_amd64.deb, 68.3mb,
open with gdebi package installer> install package> close.
/home/r/VirtualBox VMs/ now exists?

2. INSTALL VIRTUALBOX EXTENSION PACK ONTO DEBIAN.
debian> select file,
/home/r/oracle_vm_virtualbox_extension_pack-4.1.18-78361.vbox-extpack, 10.1mb,
open with oracle vm virtualbox> install> I agree> ok.

3. SETUP DEBIAN for virtualbox. md /home/r/VirtualBox VMs/share/;

4. SETUP DEBIAN for virtualbox. try sudo adduser r vboxusers.
debian> system> administration> users and groups> manage groups>
select= vboxusers> double click.
group members= select r. ok. close. close. boot.
result= win> computer> devices with removable storage.

5. SETUP VIRTUALBOX for shared folder.
virtualbox> shared folders> right mouse click> add shared folder>
folder path= /home/r/VirtualBox VMs/share/
name= share (default). select auto-mount. ok>

6. SETUP VIRTUALBOX for winxp.
debian> applications> system tools> oracle vm virtualbox. new> next>
name= winxpsp2 (type in) next>
base memory= 192mb (default) next>
new hard disc (default) next>
vdi (default) next>
dynamic (default) next>
winxpsp2, 10gb (default) next>
summary next> create next> create.

7. INSTALL WINXP ONTO VIRTUALBOX.
insert win dvd. select winxpsp2. start> ok> next> next> start.

8. SETUP WINXP for virtualbox.
virtualbox> select winxpsp2> start> devices> install guest additions>
oracle vm virtualbox guest additions 4.1.18>
next> next> install> continue anyway> continue anyway> continue anyway> finish> boot.
result= winxp> my computer> network drives>

9. NOTES. gdebi 0.6.4 2009. .ova= virtualbox virtual machine.
host= debian. guest= winxp.

Sorry, that last post was my mistake. Guest additions installs on winxp, not debian. So how to install it onto debian?