No response to your question in over a year must mean side-chaining in Virus TI actually doesn't work. It's just there for looks and to make you feel stupid for trying so hard, that you obviously lack the mental qualifications to operate it.
So what does that say to the person who searched and replied over a year later? lol
IIRC, it's up to the specific DAW being used. I believe Cubase doesn't support this but I haven't check C7 (I really should).
Logic? haven't used that in years!