Apache + RoR + subdomains

I have apache configured for mongrel cluster - usual port 80 going to 8000+. Now I want to set up a subdomain that points to a non RoR app. any clues?

thanks.

I don't know if this is the best approach, but it works for us. You
can use a VirtualHost directive in your httpd.conf with a different
doc root. For example: www.mydomain.tld proxies to mongrel (also
done in a virtual host directive) and docs.mydomain.tld goes to a
bunch of static documents.