Tethering problems with usb cable iPhone 4

This is not your typical problem I see and read on the forum, when I try to configure my iphone for USB tethering in the system preferences when I try to add a new device, only Ethernet, bluetooth Pan, Bluetooth Dun, Firewire and the rest etc etc, but no Iphone configuration like it use to before did they delete that option from OSX snow leopard because its now showing up or its not being recognized can anyone help. It is only configuring as a bluetooth and its not what I want, I want USB cable.
Thanks
iPhone 4 16 GIG IPHONE 3GS 16 GIG, iMac 27 inch i7 quad core 12 gigs of ram, Mac OS X (10.6.4)