CBQ is already part of SME 6 and 6.5, the script example is in /etc/sysconfig/cbq/
From the example you can pretty much follow and make to fit your needs.
So you should make a file in /etc/sysconfig/cbq (like cbq-1024.server-client)
with the following contents:
DEVICE=eth0,100Mbit,10Mbit #my internal network card
RATE=10Kbit
WEIGHT=1Kbit
PEAK=12Kbit
PRIO=6
RULE=192.168.100.120
BOUNDED=yes
ISOLATED=yes
Now you should be able to start cbq with: 'cbq start'. If you have multiple shaperfiles in /etc/sysconfig/cbq, you can individually start cbq-1024.server-client by adding the filename behind start, eg: 'cbq start cbq-1024.server-client'.
Remember that the only direction you can shape traffic, is outbound of a networkcard. This config file now shapes all outbound traffic, for 192.168.100.120, to 10Kbit (1KB/s). Eg. The client .120 can now download at a maximum of 1 KB/s. His upload is still my full upload capacity, but because your computer wants to know if his transmitted packets did arrive, this download-limiter also limits his upload.