Welcome!
I came across some video tutorials the other day that are quite cool, check them out
Here
When setting up MIDI devices, I always drop the Patch script file into the "Patch Script" folder for SX3. I also add a new device in OSX core Audio/MIDI setup (ignore if you are on PC)
Then, in Cubase, simply go to DEVICES: MIDI DEVICE MANAGER:INSTALL DEVICE
When you do that, a window appears with a whole bunch of synths, and your KC should be there since you put the patch script file in the "patch script" folder. Then you simply choose the output MIDI port.
Also, read the Virus manual for tips on setting up the Virus for use with a sequencer.
Good luck!