Hey, I feel your pain!
I have a similar problem. I'm on a 640 K DSL line right now (which I LOVE), and connected to a Hub.
The problem is that not only am I not able to open enough ports to run "the Zone" without causing major problem's on my roommate's end, but I cannot join JK/MOTS games, and I can host, but nobody is able to join (my roommate can join an IPX game, that's it).
So it sucks big time, that's why I've been so excited about the Rbots project ( http://rbots.massassi.net
), because it let's me play what I've been missing for months: JK/MotS deathmatch (no CTF yet).
But, on a positive note, I am going to be moving next semester back on campus (much nicer place) and they have ethernet.
Short of changing your connection (which may not be feasible), try these:
An easier way to host games or search JK.net for servers.
Fewer games than the Zone, but you can search for people with the game installed and "invite" them to the JK/MotS room to play you.
IRC, I can't remember the location.. maybe #enterthegame or something. Perhaps somebody can help me with this one. I rarely use IRC as it is.
Other than that, there's pretty much just the Zone or the game you can setup via ICQ or whatnot.
[This message has been edited by Kurgan (edited March 04, 2001).]