Routing PC line-in and line-out to USB headphones

I would like to use a single pair of (wireless) headphones at work. Right now I have three(music, Skype, and Cisco). A good pair of USB gaming headphones can solve the first two. What I can't figure out is how to route the calls from my Cisco IP phone to the headphones. Amazon has the rj9/10 adapters to coect to the headset plug of the Cisco phone and adapt to a pair of 3.5mm (mic and sound).

The question is: can I route the output of my USB headphone mic through the line-out of my PC? And the same for the output of the Cisco phone through the line-in?