I'm pretty certain you can't. However, there are a couple of options...
You can use a TOSLINK to connect to your receiver, then plug your headphones in. If your amp is capable of doing Dolby Pro Logic II, you'll have surround sound gaming.
Along those same lines, if your computer sound system can take TOSLINK and has a front headphone jack, there you go. I don't think you'll get surround gaming tho', unless your system can do Dolby Pro Logic II.