If you are looking to simultaneously connect a serial cable, and use the keypad, ZThinCable from serialio.com supports this.

The Zaurus constantly runs a pppd demon in the background waiting for a connection. This takes up the serial port and if you wish to use the serial port for something else rename /etc/sync/serialctl to any other name such as /etc/sync/serialctl_old. The Zaurus also expects to connect to a windows client and so it sends the CLIENT string which must be handled.

copy the following script into /etc/ppp/peers/zaurus. Replace /dev/ttyS0 with the serial device that is connected to the Zaurus.

-detach
noauth
nocrtscts
local
lock
connect '/usr/sbin/chat -v TIMEOUT 3600 \'\' CLIENT\c'
/dev/ttyS0
115200

Once you have a cable connected run the following command as root:

#pppd call zaurus

You should get something similar to the following output:

#Serial connection established.
#Using interface ppp0
#Connect: ppp0 <--> /dev/ttyS0
#local  IP address 192.168.130.100
#remote IP address 192.168.130.101

You should be able to ping the Zaurus at the remote ip address (192.168.130.101 in the above case).

Once you can confirm that the networking is up and running you can remove "-detach" from the script and it will go in the background when run.

The Zaurus is now on the network. IP masquerading can be setup just like it is in the USB connection for Internet access.