Because the included VST for Sonar are tied to your SN/ registration you more or less have to install Sonar to legally extract them. So no, you can't rip them from the CD.
What most do ( me included) is install the older versions oldest to newest first before installing the latest.
There's really not that much missing between 8.5 and X3.
Run each install as Custom and uncheck all the boxes but the VST's. in each version.
Make sure to run the 64 bit versions if possible, you really don't want 32 bit plug ins hanging around if you can avoid it.
The program it self doesn't take up much room , it's the content and sample libraries.
I would make a list of which VST's and Plug ins you use and then look at each version so your not installing say, X2 when you don't need to. I think I only install 8.5 to get True Piano's and V vocal.
You can do this by starting the install and get as far as the custom install check box list and observe the list of VST's.
There might be a document somewhere with the list. Anyone?