I must be stupid, I can't find the code.
Wow, no one answered this post for a long time. I hope that users who came to this project page were able to find the source code.
Here is what you need to do:
Click on the menu item "Source". This will show the "Source Repository". It is a Subversion source system view. From here you can check out the source code using the svn command shown on the right side of the page.
One thing that might be immediately useful is that on the left side of the page the link that you see there will allow you to browse the source code. So this will let you easily become familiar with the contents.