although i succedd using bandwidth limiting with cbq-script, ehmm do you heard any bandwidth limiting apps, lately i try bandwidth arbitrator checkout the link site http://bandwidtharbitrator.com/index.php
and some of bandwidth limiting project still ini beta or less than 1.0 version

is it possible using only one interface to limit the bandwidth (i tried but failed - and if i am using two interface i am succedd)

hey have you heard about mikrotik / StarOS - they sell some good router,bandwidtlimiting software (i bet not) have you used on your network environment ? (i need to to know the performance of the software) even this is not free OS, but they give some trial

thanks for your concerned