How can i set my ant.home environment variable?

Dear All:
Our company use WSAD4.03 to develope application,and we want to build the
project automatically now.
I read the article written by Barry Searle which name is Using Ant with
WebSphere Studio Application Developer.
And intent to follow it.
But I can't find the package org.eclipse.core when i set the ant.home
environment variable.
How can i do now?
Maybe download some other package ,and set it into the variable ant_home?
I do not know where to find such packages,or some articles to explain it,or
some examples.
Thanks very much.

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