The Plug-in comes either as a single .zip or compressed .tar archive. Unzipping either one of these files into a directory of your choice (referred to as <INST_DIR>) will produce three subdirectories /bin, /docs and /lib.

..
  bin/       contains wrapper scripts for different platforms
  docs/      contains the documentation
  lib/       contains all necessary libraries

Before you can use the Jalopy Ant task in your build scripts, you have to add it to your system. Maybe the simplest way is to utilize the <taskdef> element in your build script as follows:

<taskdef name="jalopy"
         classname="de.hunsicker.jalopy.plugin.ant.AntPlugin">
  <classpath>
    <fileset dir="<INST_DIR>/lib">
      <include name="*.jar" />
    </fileset>
  </classpath>
</taskdef>

If you rather want to add the provided libraries to your classpath (either by copying the libraries into the /lib folder of your Ant installation or setting up the classpath as usual), please be aware that the provided parser (aelfred-xxx.jar) is incompatible with Ant 1.4.1 or prior releases. If you happen to use one of these outdated versions, the parser library must not be copied into the /lib folder (or added to the classpath) otherwise Ant will fail to work!