When you run Hamachi, you can log in to 'channels' or servers. When you do so, you create an artificial LAN link with the host. Then, you can use the IP given next to the host's name (in my server, for example, use the IP that's next to "Zeal Omega") and type that in the serverlist screen in JJ2. That way you should be able to join.

Also, Danny, maybe it'd be handy if you joined the zealserver channel. The pass is jazz2online, and there are already a lot of players plus Beta and Omega in that channel. Of course you cna join multiple channels, so you can also remain in your channel at all times.