Deploy into Tomcat and multi domains

Hello all,

Sorry if my question is off topic as it could be more Apache/Tomcat related.

I have a WO app deploy in a public Tomcat ISP (www.4java.ca) .
The path to my appli is  www.mydomain.com/MyAppli/WebObjects/MyAppli.woa
The main component for this appli is used by a Java Client and the web pages 
use DirectAction.
This works but I not aware of the mapping used by tomcat as it was done by 
www.4java.ca.

Now, I have a second domain and I want it (in fact a subdomain) to also use 
the same appli.

I want that the URL for  the java client looks like this : 
http://app.mydomain2.com
and the web page use similars URLs : 
http://app.mydomain2.com/wa/PageWithPath?page=page1&user=dummy

How can I achive this ? What are the setting for the 2nd domain in Apache 
and the mapping in Tomcat for that ?

Thanks in advance.

Pierre