I believe that the solution was posted earlier. You should be able to leave the Tascam as your ASIO device, and insert the Virus Control as a soft synth.
You can have a zillion USB devices - only ONE ASIO device can be used at a time. So your other USB connections, like from your Fender, are fine. I have a Presonus ASIO interface plugged in with USB, and my Yamaha midi keyboard is also plugged in as USB.
Here is what that phonik guy posted earlier:
"You don't need to switch the audio drivers to use the TI2 in Virus Control mode. You would only switch the audio driver if you want to use the Virus TI2 as a soundcard for recording or monitoring. If you are only using it as a plugin via USB, insert the Virus plugin as a synth and it will automatically sync with the hardware. You'll then be hear the audio through your Tascam, just as you would with any other soft synth, the difference being that the Virus hardware is actually generating the sound and using its own processing power, rather than your CPU. Hopefully I understand your question correctly."
Read the above carefully - this is what will work for you to control the TI2 through Sonar, WHILE using the Tascam as your actual selected ASIO device in Sonar. Make the Virus Control insert as a synth. It is a PLUGIN.
So, please give the above a shot and post back with results,
Bob Bone