you can use target install.demo.noeclipse which would not attempt to download and install eclipse at all. Moreover you can download eclipse yourself and the configure it's location in the build.properties so installer will not attempt to download it. Look at the documentation for more details about the installation of various components.
When it comes to eclipse url - jbpm 5.4 was released November 2012 and since eclipse is a 3rd party application (from jbpm point of view) it can guarantee its location as eclipse team might (and did in this case) for the download to a different location.
HTH