2 things to try:
1) You might try selecting your Mac's output to "line output" in your Mac's system preferences. iTunes should then play through that. Run a cable from the Mac's line output to the line input of an open channel, and that may solve your problem.
2) You could use the 16.0.2's flexible inputs router. Click the Setup tab in Virtual StudioLive, then set the Flexible Inputs Router to "Analog Inputs 15/16." Be sure to engage the firewire return on 15/16 on your board. Now all audio from the computer will be sent to that channel instead of the Main fader. Now, assign it to as Aux, and patch a cable from that aux to an open channel to get it back into your software.
I think I'd go with option 1, but I think either way should work. I think there's a way to route signal via firewire from the computer to the board and back again on the larger StudioLive consoles, but not on the 16.0.2. Hope that helps!