I was actually going to try getting Hyperion installed/working once i get some other things squared away. If im not mistaken, RetroPie is built on Raspbian. I would try following that wiki first. First thing i would try from an SSH session is “netstat -tnl” to see what ports listening. If you dont see the default open then that would be a place to start. Change the default port in the hyperion config file. I think the default port is 19444 or 19445. You can also alter your iptables to open the port. I think the command to do so is:
sudo iptables -A INPUT -p tcp –dport 19444 -j ACCEPT
sudo iptables -A INPUT -p tcp –dport 19445 -j ACCEPT
Goodluck and I hope its as easy as opening the ports because in the next few days ill be giving it a go too.