I was having problems with this, but the answer isn't hard.
Open a root console, and modprobe acm hid and pxa27x_bi
The host machine should now pick up the Z (you can check using lsusb)
Check on the Z, using ifconfig -a, you should see a usbd0 device.
Now you can ifconfig usbd0 192.168.129.201 and add your gw, route add default gw 192.168.129.1 or what have you. /etc/resolv.conf also needs to be edited with your dns servers.