Access internal network by LAN and internet by Wifi?

I'd like to be able to bypass my company's firewall for internet access (long story, just trust me; also this is not a nefarious plot, it's a business need) yet still access the files on our file servers/use Office Communicator and Outlook. My solution would be to get a mobile hotspot and connect to it using wifi. And keep the ethernet connection to connect to the file server/OC and Outlook.

Can I connect to one network via LAN and then another network via wifi? Can I specify which for each connection?