The download link for Eclipse in the build.xml is 404. It has been changed at Eclipse.org.

Change line 253-254 from this:
<get src="http://download.eclipse.org/technology/epp/downloads/release/helios/SR2/eclipse-java-helios-SR2-${download.type}.${download.extension}"
dest="${install.home}/lib/eclipse-java-helios-SR2-${download.type}.${download.extension}" />

To this:
<get src="http://archive.eclipse.org/technology/epp/downloads/release/helios/SR2/eclipse-java-helios-SR2-${download.type}.${download.extension}"
dest="${install.home}/lib/eclipse-java-helios-SR2-${download.type}.${download.extension}" />