1. Extract openfire with the name in /opt/openfire_2
2. Go to /opt/openfire_2/bin/ and change the name of the openfire file to openfire_2
3. Go to /opt/openfire_2/conf/openfire.xml and change the console ports from 9090 and 9091 to 9098 and 9099
4. Create shortcut sudo ln -s /opt/openfire_2/bin/openfire_2 /etc/init.d/
5. Run sudo service openfire_2 start
6. Open the browser localhost:9098 and start setting up as you want with different domain.
Do not forget to change the xmpp ports to something else than 5222.