Follow the procedure described in the document at the URL http://www.zeroshell.net/eng/qos/ to build a QoS bridge or router.
At the point in which you have to classify the traffic, instead to use the layer 7 filters in the Qos classifier, you must specify the source MAC address of your hosts.
Keep in mind that with the source mac you only are able to control the uploading bandwidth. To control the downloading one you can use the destination IP addresses of the host. To understand which interfaces you have to use, read the above document.