briefly, the zaurus can be set to either usb mass storage or ip-over-usb; with the latter than Z gets the IP address 192.168.129.201
set the desktop machine to 192.168.129.1 and you should be able to ping the zaurus and ssh into it; the interface on the PC should be "usb0", so just (as root), "ifconfig usb0 192.168.129.1 netmask 255.255.255.0".
might want to set a default route on the zaurus with "route add default gw 192.168.129.1" so your PC can be a router for it, and then you can install packages directly from your zaurus with "ipkg update ; ipkg install packagename"
once you've proven that, the rest is tweaking!