Sorry to potentially rain on your suggestion. We over on TNT were playing about with this last night, and have done a bit of research.
Line 1: Server/(World) Name - This is where your Lava Survival Round/Deathrun Round bit is at the moment. This can only be changed when the world/server is loaded we think.
Line 2: Server/(World) MOTD - We haven't managed to get this to work. But it's based on the MOTD, and ditto above, cannot be updated.
Line 3: User.detail, this will stay until changed, and can be live changed in game eg the Time Left/Lava time.
Lines 4-X: Alerts, these can be messages or login/out alerts. However, each new one creates a new line (ie no easy way to update without clogging the screen) and each one only lasts 9? seconds before disappearing.
Unfortunately for Arcius, the messages are (and without changing the client, can) only be on the right hand side.
I don't know how this will affect the ideas, but I hope this has helped.
PS: I like the idea of seeing the record time for death run maps, and this could probably easily be put alongside the current time, both in the live and typed command.