The source base of Asmeta (including the documentation and the web site) is maintained in a Subversion repository at SourceForge. The repository's URL to checkout asmeta repo from svn is
For instance, by using tortoisesvn, you can checkout the repo in this way:
You might also browse the Subversion repository online.
The file http://sourceforge.net/p/asmeta/code/HEAD/tree/readme.txt describes the organization of the repository.
Working with the Asmeta sourcesThe better way is to use eclipse and checkout the projects from the svn.