The WLab source can be obtained from its Subversion repository at svn://wlab.paulneve.com .
Create a directory that will store the WLab source, navigate to it in a command line, and then issue the following SVN command:
svn co svn://wlab.paulneve.com/WLab .
This will download a complete set of the WLab code, including the WLab application itself, and the modified versions of TightVNC and Jumpgate needed for its operation. If you only want WLab itself, and have no intention of working on the other components, append WLab to the end of this command line – note that this is case sensitive, so capital-W, capital-L, lower case A and B.