<p>I'm talking about <a href="http://en.wikipedia.org/wiki/Quality_of_service" rel="noreferrer">http://en.wikipedia.org/wiki/Quality_of_service</a>. With streaming stackoverflow podcasts and downloading the lastest updates to ubuntu, I would like to have QoS working so I can use stackoverflow without my http connections timing out or taking forever.</p>

<p>I'm using an iConnect 624 ADSL modem which has QoS built-in but I can't seem to get it to work. Is it even possible to control the downstream (ie. from ISP to your modem)?</p>

I don't know if this will help you, but I've never been a fan of using the ISP provided box directly. Personally I use a
Linksys wrt54gl
, with
DD-wrt
, behind(DMZ) my ISP provided box.
DD-wrt has excellent QoS management.
Sorry I can't be more help with your existing hardware.