Networking with two bb connections

Hi all, I'm working at a TV productions company and we have to upload hefty movie files to TV stations daily, and so have just got ourselves a dedicated broadband line for uploads, so as not to clog up the normal connection we use for the web/emails.

Now, all eight of our macs are connected up through a router and ethernet.

One of our macs, to be used for the uploads, needs to connect up to the 2nd broadband line, but STILL be conneted to the other macs via ethernet, so that we can move the files around.

I don't really see a way of making this happen. If I try to connect to the 2nd broadband line via wireless, the ethernet still takes priority.

Any tips would be greatly appreciated!

Michael