To get the source, just go to https://github.com/balu-/FSyncMS and clone the git repository or download and extract FSyncMS to /var/www/ so thet after this process, there can be found a folder named /var/www/FSyncMS. Now do chown www-data:www-data -R /var/www/FSyncMS and go to http://yourdomain.com/FSyncMS/ and setup your mysql connection. Remove /var/www/FSyncMS/setup.php and try to connect to http://yourdomain.com/FSyncMS/index.php/ over the Firefox sync settings panel. Thats it.

Further Informations:

http://www.synology-wiki.de/index.php/Weave_Minimal_Server_f%C3%BCr_Firefox_Sync

http://www.ohnekontur.de/2011/07/24/how-to-install-fsyncms-firefox-sync-eigener-server/