USB tethering with Cyanogenmod and Gentoo

First ensure that your kernel config supports networking via USB:

CONFIG_USB_USBNET=m
CONFIG_USB_NET_CDCETHER=m
CONFIG_USB_NET_RNDIS_HOST=m


Then create the symbolic link for the usb0 network interface:

cd /etc/init.d/
ln -s net.lo net.usb0


Plug in the phone and enjoy surfing:-)

More info see here.