Virtual Host and Intranet Webtop

I'm trying to setup a virtual host-based connection. When users connect to the virtual host, I want them to auto-launch an Intranet Webtop. I've followed the documentation on setting up the virtual host connection and I've configured the Master group for the Intranet Webtop, but when I log in as a test user, they get the normal webtop. Has anyone done this before?