For in-depth help, the best thing to do is file a service request. I do recall some combinations of versions are incompatible; what version of Virtuoso and what version of Calibre?
The instructions for integrating Calibre Interactive (kick off full Calibre runs, look at results) with Virtuoso are in the Calibre Interactive manual -- one of the appendixes. If you are asking about Calibre RealTime (does the on-the-fly DRC checks while you move shapes) there's also a quick reference card. Both should be available in $CALIBRE_HOME/docs/pdfdocs .