I have an MSI PC54g, and even though it uses the broadcom chip set, it is not supported. The first way I got it to work was with driverloader but that is a non-free solution. You get to try it for 30 days then you have to purchase the driver or it will stop working.

I then found ndiswrapper and that solved most of my problems. The only problem I hve now is that I have to do the wlan configuration every time I reboot. Give these steps a try and see if this helps

1. On the command line type lspci nad see if your card is detected.
2. If the card shows up here, download and install ndiswrapper
3. You will need the windows drivers for your card.
4. Follow the instructions to load your driver
5. Go to Network/Internet|Network Card configuration
6. Follow the prompts and you should be good to go.

Good luck

Jim