Setting the class path was a bit tricky , I did the following on mac(10.6.8) terminal before running the java command provided by Philp above :
ClassPath Setting :(execute this one after other on the terminal )
export JAVA_VERSION=1.6
export JAVA_HOME=/System/Library/Java/JavaVirtualMachines/1.6.0.jdk/Contents/Home
export GRINDERPATH=/Users/cdname/grinder-3.11
export CLASSPATH=$GRINDERPATH/lib/grinder.jar:$CLASSPATH
export PATH=$JAVA_HOME/bin:$PATH
java -classpath $CLASSPATH net.grinder.Grinder
I included this to /etc/launchd.conf, and run grep -E "^setenv" /etc/launchd.conf | xargs -t -L 1 launchctl
In the grinder.properties file set : grinder.useConsole = false
Now run the .py file:
java -Dgrinder.script=csaTest.py net.grinder.Grinder