You need to follow the steps for clustering the Meeting server which include creating a WebSphere proxy to handle HTTP/S.
If you want for external people to access then you need to think about how you are going to traverse the firewall/s as SIP and audio and video have problems. Generally you can deploy Edge components which include a TURN server and a SIP Edge proxy which is similar to the WebSphere (HTTP/S) server that sits in front of your Meeting server.
You should spend some time thinking about how you want this deployed and discuss with your network people the implications.
The Edge components allow you to keep the majority of your servers internal apart from the Edge components which sit in the DMZ and are used to traverse your firewalls. You could deploy everything into the DMZ but the risks are higher as you have less security layers between the internet and your servers.
The following is a good description of how to deploy Edge components.
In the ST9 wiki there are various examples of deployment you could consider. You would do well to stop where you are at and plan for what and where the remaining nodes will reside.
It is possible to tunnel all traffic over 80 and 443 including the TURN server but you will need to separate out your nodes so no more than one thing is listening on 80 and 443 unless fronted by a WebSphere proxy listening on those ports.