Well, assuming you are using a router and not a direct-connect to the internet, you can do the following:
1. Go to dyndns.com and get a free host name for dynamic DNS. For this example, let's assume you get something like
www.mycommandersite.dyndns.org. Be sure and download the "DynDns updater" utility and install it on the HA pc. That's the piece of software that lets dyndns.org know when/if your outside (Internet) i.p. changes.
2. On the HA pc, change that pc to a static i.p. address in the same subnet as the rest of your network. You do this from ControlPanel => Network Connections.
3. In the router, set up "port forwarding" so that requests that arrive on port 6003 (the Commander port) are sent to the static i.p. address of the HA pc.
Now when you're outside your network, you should be able to connect to
www.mycommandersite.dyndns.org:6003 and be routed right to Commander on your HA pc.
Make sense?
ITguy