Today, I installed Hyper-V on my Windows 8 machine so I could make a VM for a demo I'm giving later this week. I set up the virtual network as an internal network, and then used Windows 8's internal bridging system to bridge the internal network over to the live WiFi.
DISCLAIMER: You're about to mess with registry settings and network settings. You could seriously break things if you do it wrong, and there's no guarantee I've done everything right. Make sure you have a backup before doing anything like this.