So I had a number of problems doing this, but I succeeded, and here's a few notes on that.
1. Might have to set the JAVA_HOME. In Windows you do this with
set JAVA_HOME=C:\Program Files\Java\jdkx.x.x_xx
Where the x letters are the version number of the JDK.
2. When you go to the download link, you'll need to click on "Branches" then you'll see the branches where you can download a .zip, .bz2, or tar.gz of the files in the branch that you'll need in order to build this.
Also thanks to p000ison for posting this. I found this was the best way to go about it, having the projects in the bin directory of ant.