OK so I tried this but It crashed and I got this
---- Minecraft Crash Report ----
// Oh - I know what I did wrong!
Time: 5/5/13 3:22 PM
Description: Exception in server tick loop
java.lang.NoSuchMethodError: net.minecraft.world.WorldServer.L()Lnet/minecraft/world/storage/WorldInfo;
at keepcalm.mods.bukkit.nmsforge.DimensionManagerImpl.setWorld(DimensionManagerImpl.java:141)
at net.minecraftforge.common.DimensionManager.setWorld(DimensionManager.java:63)
at net.minecraft.world.WorldServer.<init>(WorldServer.java:142)
at net.minecraft.server.MinecraftServer.func_71247_a(MinecraftServer.java:238)
at net.minecraft.server.dedicated.DedicatedServer.func_71197_b(DedicatedServer.java:186)
at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:430)
at net.minecraft.server.ThreadMinecraftServer.run(SourceFile:573)
Help please this is urgent