With 2.6.x kernels you don't need to do any patching - everything you need is already in the kernel.
The settings you want are in the usb section of the kernel config.
I've been connecting my Z to my gentoo box for over a year now, all I ever did was compile the kernel, make an alias for usbnet to usb0 in /etc/modules.d/aliases and plug in the Z.
Make sure your Z is set to USB TCP/IP before you plug it in (otherwise you'll get an error whe you change)
Stu