diff --git a/README.md b/README.md
index 904c3e819ced9d4c59efc58c7f064c50dd058fa7..6d182aed0edeb4af5dffea90e86ba7a13693b542 100644
--- a/README.md
+++ b/README.md
@@ -2,3 +2,24 @@ genjava
 =======
 
 RosJava message definition and serialization artifact generators.
+
+For future reference, executing the generator from the command line requires a command of the following kind:
+
+```
+java -classpath .:./message_generation-0.1.16.jar org.ros.internal.message.GenerateInterfaces
+```
+
+This doesn't work exactly though because it doesn't pull in the full classpath. Make sure that is set to include everything you need. You'll also need arguments of the kind we're currently using in the hydro groovy plugin:
+
+```
+        def generatedSourcesDir = "${p.buildDir}/generated-src"
+        def generateSourcesTask = p.tasks.create("generateSources", JavaExec)
+        generateSourcesTask.description = "Generate sources for " + pkg.name
+        generateSourcesTask.outputs.dir(p.file(generatedSourcesDir))
+        /* generateSourcesTask.args = new ArrayList<String>([generatedSourcesDir, pkg.name]) */
+        generateSourcesTask.args = new ArrayList<String>([generatedSourcesDir, '--package-path=' + pkg.directory, pkg.name])
+        generateSourcesTask.classpath = p.configurations.runtime
+        generateSourcesTask.main = 'org.ros.internal.message.GenerateInterfaces'
+        p.tasks.compileJava.source generateSourcesTask.outputs.files
+```
+