This is something I've wondered after for a while and I couldn't think of a different title in under 80 characters. What I'm trying to do is use both my WiFi and Ethernet at the simultaneously, on different networks. Is there a way to have PowerShell open a connection, as if opening a workflow, using the Ethernet for an internal/ad hoc network connection, while maintaining my Internet connection on my WiFi? For example, I'm reprogramming my firewall and don't want to put it on my network yet. Should I just use ROUTE to say anything going to my firewall at IP(a) use InterfaceAlias "eth2" and everything else use InterfaceAlias "WiFi"?
This isn't a really a powershell question. It's more of a Windows/Networking question. However, you can just configure your LAN NIC with it's IP and Subnet, and not configure a Gateway address on it. That way all traffic for the local network of that interface will go out of that interface. All traffic for the local network of the Wireless network will go out the wireless interface, and all traffic for unknown networks will go to the default gateway, which is on the wireless network.