Taken from: http://blogs.msdn.com/b/nicold/archive/2008/04/15/how-to-use-hyper-v-with-a-wireless-network-connection.aspx
Hyper-V doesn’t manage wireless networks “by design", however this can be worked around.
Create an “Internal Virtual Network” (IVN) with a name of your choice and the default settings.
On the Hyper-V server add the "Network Policy and Access Service" role with “Remote Access Service” and “Routing”. Select “Custom Configuration” and “LAN Routing only” and “Start Service”.
Add a static route to your WiFi router to forward requests for the Hyper-V guests to the Hyper-V host.
To make one of the guests visible in the Internet you can use port forwarding to the guest IP and port.
To allow other devices on your wireless LAN to access guests, add a static route on each machine connected to the wireless