I don't know much about Eclipse plugins, but the mcc18 plugin I've used is simply a jar file (which is actually a zip archive). If you extract that, you should have all of the source. It's an XML file and some package meta-info.
The version on Astronouth7303's site is also a jar file, and should be similar.
http://www.astro73.com/download/eclipse/fdt/plugins/