Default Tethering through WM5 device on mac

Hi guys,
Actually I am trying to configure Dial up on Macintosh Mac os x on PPC machine.But my problem is that when I connect it through USB , it is not detected on network port whether its working fine with Bluetooth. So I want to ask the possible reasons of this problem and also that how can we overcome this problem? And please also tell me that What are the WM5 devices that are working fine with mac machines via USB.

Thanks
Subodh