The testing version is updated to 2.3.1
deb
http://www.vollstreckernet.de/debian/ testing amule-stable wx
wx is empty by now, but will contain a new version when it's needed, so you can ommit this entry.
amule-stable will become empty, too, when 2.3.1 arrives in testing and contains plasmamule, which isn't the case for packages uploaded by now.
For sure, you can get the sources for selfcompile the usual way via:
deb-src
http://www.vollstreckernet.de/debian/ testing amule-stable wx
You can combine those two possibilities to get just what you want.