You really should not post the same thing in multiple sections of the forums, as it makes it difficult to keep all the replies in one thread.
Thus people, including yourself, are forced to check multiple threads instead of one for answers. It's also a bit annoying to have to keep track multiple threads.
Also, if someone comes upon one of the threads later searching for the same answer you are, they might not find it in its entirety. They might find one thread and see no answer in it, then skip the other two thinking it's the same one.
Anyway, given you've posted it three times here, hopefully you've posted the same thing on the Cubase forums? That would seem the best place to get an answer to automation in Cubase.
I don't use Cubase, so I'm not sure if this is an issue with the Virus or Cubase. When I tried this in Reaper, the mod matrix slots could not be automated. I suspect that may be a limitation of the Virus.
However, if you make your source slot one of the controls, e.g. Control 09, give the oscillator pitch destination slot a non-zero value, and set one of the Soft Knobs destination to that control, you can automate the soft knob. I'm not sure if that will do exactly what you want, but I kind of suspect it's the closest you'll get.