This is is short howto use Pocket PC (Windows CE) handhelds with USB and Knoppix. No warranties given.

This software does all the magic:
http://synce.sourceforge.net/synce/

If you have a hd install, just install synce via apt-get.

However, if you are running from CD, there is also a chance to connect to your USB PPC:

Code:
# do this as user knoppix
# use /home/knoppix/synce as working directory
# caution: dccm does NOT work as root!

cd /home/knoppix
mkdir synce
cd synce

# get and unpack synce
wget http://synce.sourceforge.net/debian/...0.7-1_i386.deb http://ftp2.de.debian.org/debian/poo...0.8-1_i386.deb http://ftp2.de.debian.org/debian/poo...0.8-1_i386.deb http://ftp2.de.debian.org/debian/poo...0.8-1_i386.deb http://ftp2.de.debian.org/debian/poo...0.8-1_i386.deb
unp *.deb -u
rm -f *.deb
rm -f control.tar.gz data.tar.gz debian-binary
rm -rf control

sudo insmod usbserial
sudo insmod ipaq vendor=0x3340 product=0x3326
# use your PDA's own IDs instead
# didn't work before Knoppix 3.3

# dmesg
# should show:
# usbserial.c: PocketPC PDA converter now attached to ttyUSB0 (or usb/tts/0 for devfs)

### now you have to edit some files by hand
### correct the path prefix=/usr to prefix=/home/knoppix/synce/usr
mcedit ./usr/bin/synce-serial-config
mcedit ./usr/bin/synce-serial-start
mcedit ./usr/bin/synce-serial-abort

sudo ./usr/bin/synce-serial-config ttyUSB0

### and again hand edit the path
# sudo mcedit /etc/ppp/peers/synce-device

# Start dccm
LD_LIBRARY_PATH=./usr/lib/ ./usr/bin/dccm

# open the link
sudo ./usr/bin/synce-serial-start

# now use the tools as user knoppix
export LD_LIBRARY_PATH=./usr/lib/
 ./usr/bin/pstatus
./usr/bin/pls /

# close the link
sudo ./usr/bin/synce-serial-abort
Works fine for me.
But with some more magic, you can even apt-get KDE integration... I'm working on this at http://klik.berlios.de