Sonar X3d and Access Virus TI2 Problem

Fellow TI2 owner here. I don't have X3d, but perhaps I can still help. I am a bit confused on your question. I assume you want to have multiple MIDI channels in Sonar control multiple MIDI inputs on the Virus, right? Why do you want more than one "output?"
 
Let's see if this clears it up. Overall, there are 2 methods to insert the VC (Virus Control).
 
First Way:
1. Turn on the Virus. Wait for the USB-connect sound.
2. Start up Sonar and a new project.
3. Find the Virus TI instrument in the Browser and drag-n-drop into the Track View.
4. On the popup window, select MIDI Source and All Synth Audio Outputs: Stereo.
5. VC should load and initialize.
6. Check the Virus' MIDI track. Note that it's output is Virus-TI 1 (in my case it's 5-Virus-TI 1). This is the ONLY input to VC. No more, no less.  Also note that it's channel (underneath the MIDI FX bin) is "NONE", but it indeed sends MIDI-data to MIDI-channel 1 on the Virus.
7. Now, let's create a new MIDI channel for the VC (the quick-n-easy way). Clone the original Virus MIDI track.
8. Change the new channel's MIDI channel to 2...3...4...etc. Do this with the drop-down menus that are located BELOW the FX bin. Don't worry about setting the Bank and Programs.
9. Set your patches accordingly within VC and play the various MIDI channels. You should experience the multitimbral goodness now.
 
Second Way (But not as efficient, IMO):
1. Create new Audio track.
2. Drop VC into the audio track's FX bin. VC should load and initialize.
3. Create new MIDI channel(s). Set output to Virus TI 1.
4. Change the various MIDI tracks' channels to 1...2...3...4...etc.
 
I say "not as efficient" because if you want more audio channels, assuming you have your VC set up to do more than one, stereo USB-audio channel, then you will have to manually select them as different inputs to the various audio channels that you have set up. A benefit, perhaps, would be to have the same audio inputs to different audio tracks and process the audio streams in different methods, e.g. different FX plugins, and cross fade them around in your mix.
 
Well, I hope that helps!