Want to use no internet connected router

Both computers are xp.

Computer A(home edition) has a wireless mobile broadband internet connection. Computer B(pro edition) no internet connection.

Router not connected to the internet.

When I use the router for the 2 computer network, computer B does not see the wireless mobile broadband internet. With the 2 system ad hoc together, computer B does see the wireless mobile broadband internet.

What can I change on the router to make computer B to see the wireless mobile broadband internet?