Well I don't have the specific instructions. The way I was using it was like so:
1) At my house, I believe I had my router set-up to forward ports 5050 to 5090 to the computer with Axon installed on it (port forwarding instructions on www.porforward.com)
2) I created an extension in Axon for the external/remote user
3) On the remote computer at the second home I also opened the router and forwarded the ports used by the Softphone on that computer.
4) I set-up the softphone to use the extension I created
5) And it worked, incoming and outgoing calls worked without problems
For me it wasn't too difficult to get it to work, but I know many other people have had many problems achieving remote extensions and some users even tried to setup VPN connections to get it to work.