I think you need dedicated hardware for what you want.
I've been trying to use my laptop (Lenovo IdeaPad Y580) as a wireless adapter for my Xbox 360 by bridging the LAN/Wireless networks and connecting the Xbox to the laptop via Ethernet. The wireless works fine normally, but when I plug the Ethernet cable into the computer, the laptop automatically disables WiFi and changes to a LAN connection. It doesn't give any options whatsoever to reconnect to wireless, just forces me to use the Ethernet connection. As soon as the cable is removed the wireless connection returns, but for what I'm trying to do to work, I need both LAN and wireless to be working simultaneously, and the wireless providing the Internet connection. I've also tried connecting the laptop to a router via Ethernet and received the same result, so I'm pretty sure it's something on the laptop that's causing it. Is there a way to change this so the laptop can use the wireless connection while plugged into another device via Ethernet? Thanks to all who respond.