We use TMG as our edge firewall and publish the website through it (web publishing rule with external IP)

I would like to add a webcam to the site and use the existing external ip (we have no more spares) and publish it as www.website.co.uk\webcam so that link goes direct to the webcam feed through TMG - is that possible? I've tried a few configurations but it always seems to go to the web server itself, which reports that \webcam doesn't exist (which is true!)