Dual WiFi network cards route outgoing traffic to specific cards Let's say I have two wireless networks I can connect to, alpha and beta. 

In this scenario the alpha wifi gives me access to a specific intranet and specific sites I need to access, and blocks specific sites. For example http://someblockedsite.com. 

The beta connection however does not have access to the intranet but does allow access to the blocked sites.

The case now is that I'm switching back and forth between the two connections, and it's really a pain point, it's slow and confusing.

I'm on a Macbook Pro, and I've been thinking about purchasing an external WiFi dongle with which I would be able to connect to one network with my Macbook WiFi card and the other with the external dongle. Ideally I would be able to use something like the hosts file to modify the outgoing traffic on my machine so that when I access one domain http://onlyalpha.com it will use the alpha connection and when I access the http://onlybeta.com site it will use the beta connection.

Is something like this possible?
This would probably be a lot of work for people that don’t set up networks for a living, but let’s assume you have a good reason and propose a solution.

You would need to serve two networks so that each AirPort connects to a different network segment so each could have different routing or different DNS. All the setup would be on the network side and you wouldn’t really need to do anything other than set up DHCP on each wireless adapter and possibly set up a hosts file over-ride or tunnel traffic to onlybeta.com through a server / gateway on the network for the beta wireless card.