Now that eclipse 4.5 is out and the eclipse team decided to not build the so-called \"delta-pack\" anymore, I don\'tknow how to perform a PDE headless build with ant..
That "Building" wiki page also describes how to "roll your own" delta pack.
I just added that description, and ant script, last night, 6/24. I think that example script produce a better Delta Pack than what is in the R-4.5-201506032000 directories. I'd be interested in hearing of user experiences, say in Eclipse bug 470913.
[And, admit, I still "owe" the community an example of doing a headless build, for previous delta pack users, but it will center around doing a p2 oriented build. There place to begin reading about that is in the Eclipse Help, search for "p2 builds" and "fetching from repositories". ]