Java doesn't use the PATH
variable.
To specify the classpath when running a java application use the -cp
parameter for the java
command.
Inside your batch file (the .cmd file) find the java
command and add the needed jar file:
java -cp somefile.jar;\path\to\jython.jar someclass.MainMethod
Please don't use the deprecated CLASSPATH
any more.
For more details, please see the Java documentation:
http://docs.oracle.com/javase/6/docs/technotes/tools/windows/classpath.html#tooloption