title: Override properties in an Ant target
body: <p>We use lots of properties in our Ant scripts, run from Eclipse. I want to set up a parallel deployment which builds the project with slightly different property values, and deploys to a different location... deploy location is also a property.</p>
  
  <p>[How] can my new target update some properties to custom test values and then run the normal target to get the desired result?</p>
  
  <p>Simple sample script is very welcome, I only know enough Ant to get by :)</p>