This is the medical approach. I could try to learn tools like UML to model the plugin with the added benefit of using sophisticated tools to produce code from the model but that is not my preferred approach.
Anyway I downloaded wxglade from https://bitbucket.org/agriggio/wxglade/ as zip file. Unpack it into a directory like /home/user/wxglade and you are good to go. Find the wxglade shell script and change it to make it find wxglade.py in the same directory. Just remove the /usr/lib/foo stuff.
Fire it up and either start a new project or start from one of the wxg in the GNUmed CVS source tree. Oh I don't have the CVS tree copied yet. So lets do that now.
Heading over to wiki.gnumed.de in the Dowload section I am presented with the option to either download a snapshot package or get a copy of the CVS tree. SInce I will probably need to get updates often I will go for the CVS option.
Update: GNUmed has swithed to GIT for source code management. New guide is available.