Fix build script. Add a sample JSON file. You'll need the newest Launcher code to run this.

fml/FML152.json

@@ -0,0 +1,69 @@
+{
+  "id": "FML152",
+  "time": "2013-03-20T12:00:00-04:00",
+  "releaseTime": "2013-03-20T12:00:00-04:00",
+  "type": "release",
+  "minecraftArguments": "${auth_player_name} ${auth_session} --gameDir ${game_directory} --assetsDir ${game_assets} --tweakClass cpw.mods.fml.common.launcher.FMLTweaker",
+    "libraries": [
+    {
+      "name": "cpw.mods:fml:5.2"
+    },
+    {
+      "name": "net.minecraft:launchwrapper:1.3"
+    },
+    {
+      "name": "net.sf.jopt-simple:jopt-simple:4.5"
+    },
+    {
+      "name": "argo:argo:2.25_fixed"
+    },
+    {
+      "name": "org.ow2.asm:asm-all:4.1"
+    },
+    {
+      "name": "org.lwjgl.lwjgl:lwjgl:2.9.0"
+    },
+    {
+      "name": "org.lwjgl.lwjgl:lwjgl_util:2.9.0"
+    },
+    {
+      "name": "net.java.jinput:jinput:2.0.5"
+    },
+    {
+      "name": "org.bouncycastle:bcprov-jdk15on:1.47"
+    },
+    {
+      "name": "com.google.guava:guava:14.0"
+    },
+    {
+      "name": "net.java.jutils:jutils:1.0.0"
+    },
+    {
+      "name": "org.lwjgl.lwjgl:lwjgl-platform:2.9.0",
+      "natives": {
+        "linux": "natives-linux",
+        "windows": "natives-windows",
+        "osx": "natives-osx"
+      },
+      "extract": {
+        "exclude": [
+          "META-INF/"
+        ]
+      }
+    },
+    {
+      "name": "net.java.jinput:jinput-platform:2.0.5",
+      "natives": {
+        "linux": "natives-linux",
+        "windows": "natives-windows",
+        "osx": "natives-osx"
+      },
+      "extract": {
+        "exclude": [
+          "META-INF/"
+        ]
+      }
+    }
+  ],
+  "mainClass": "net.minecraft.launchwrapper.Launch"
+}

fml/build.xml

@@ -369,6 +369,7 @@
     <signjar alias="FML" jar="${basedir}/target/${universal.jarname}.zip" keypass="${sign.KEYPASS}" keystore="${env.JENKINS_HOME}/${sign.KEYSTORE}" storepass="${sign.STOREPASS}" verbose="true" />
   </target>
   <target name="makebinpatches" depends="buildenvsetup,makeversion">
+    <delete dir="${basedir}/binpatch" verbose="true"/>
     <java classname="cpw.mods.fml.common.patcher.GenDiffSet">
       <classpath>
         <pathelement path="${mcp.obfoutput}/minecraft"/>