You want to distribute an application through webstart using Pack200
(Java 1.5+) compression ?
ANT itself has no Pack200 task - the one from https://java-pack200-ant-task.dev.java.net/
can only process a single file.
I wrote a new one which allow the use of an inner fileset to specify the set of JARs to (re)pack.
It is complete written from scratch using the official Java API and is available with sourcecode
under the BSD license.
You can find the ANT task and other usefull stuff on my website http://www.matthiasmann.de
Ciao Matthias Mann