I tried simply replacing darkcanuck.net with literumble.appspot.com, but apparently it's more complex than that. Roborumble can't download the ratings file and can't upload results.
That should be all you need, make sure you replace the URL for all 3 instances. The default Robocode install should come with the correct URLs now.
A couple of things. One, the URLs no longer have "/rumble/" like the used to. Removing that fixed the URLs. Also, it appears the accepted clients are now 22.214.171.124 and 126.96.36.199. It appears the 1.7.3.x clients are no longer accepted. I'll have to check, but the 1.8 Robocode clients may require Java 1.7. Guess I'll find out in the next few days. I'll try to update this page, but I am kind of learning as I go to figure it all out.
I updated the "From standard Robocode" section. Additional updates are required to bring the page up to date. Someone needs to bring all the superpack info up to date. I'm not personally up to date on what superpacks are available. If no one else updates it, I'll get it figured out in a few days and update it.
I'm sure the "major.minor" thing has come up before, but I didn't find it in a quick search. The list of robots I see this on includes: alpha.RainingFire ancientpyro.megas.kbot.KBot bots.UberBot bumblebee.Bumblebee cb.DeepThought cb.droid.Polyphem cb.Femto cb.mega.Enigma cb.micro.Haiduc cb.nano.Chasseur cb.Sabertooth cb.test.Provocateur com.timothyveletta.FuzzyBot daemons.DizzyA dhn.Immortal fromHell.C4H10O kb.PingPong kenran.InfiniteObscurity Lo_Ian.Gandalf_V4 mae.Mae1 mb.Beast mb.Monte qualidafial.MajorDick rc.RCBot romz.robot.circular.WildRabbit romz.robot.guessfactor.TeasingFox romz.robot.Test sfergus.Terminator stranger.nano.TestBot suh.micro.MirrorPM suh.micro.WallPM suh.nano.AntiGravityL suh.nano.CornerRL suh.nano.MyFirstAdvancedRobot suh.nano.RandomPM tkt.RedShift zignd.ZigIndexOutOfRange
Yikes! We're only supposed to require Java 6. And in the past I've removed bots from the rumble for requiring Java 7 and put a note on the participants page for those bots. But with that many, I wonder if it's time for us to just say to use Java 7?