In JDK5.0, you can use the javaagent option that does not require a separate Classloader. Here are the ant snippet from one-test-pojo , for example.

<target name="one.test.pojo" depends="compile" description="run one junit test case.">
   <junit printsummary="yes" timeout="${junit.timeout}" fork="yes">
      <jvmarg value="-Djboss.aop.path=${output}/resources/pojocache-aop.xml"/>
      <jvmarg value="-javaagent:${lib}/jboss-aop-jdk50.jar"/>
      <classpath path="${output}/etc" />
      <sysproperty key="log4j.configuration" value="file:${output}/etc/log4j.xml" />
      <classpath refid="lib.classpath"/>
      <classpath refid="build.classpath"/>
      <formatter type="xml" usefile="true"/>
      <test name="${test}" todir="${reports}"/>
   </junit>
</target>