Gert, there's an earlier message that I think explains what he's aiming for.

Essentially, I think it's something like this:
www.mydomain.com:80 -> live site
www.mydomain.com:81 -> preview site
www.mydomain.com:82 -> test site
(or similar)

I know it's possible to have multiple ports going to the same site (at
least in Tomcat, I assume with Resin too), but no idea if you can
change the webroot/context based on the port?