For a complete installation tutorial on Mac OS X, refer to github.com: run ClamAV on Mac OS X with Homebrew.
If downloading main.cdf is slow, manually download it from http://database.clamav.net/main.cvd (also http://database.clamav.net/daily.cvd) and put them under /usr/local/Cellar/clamav/0.98.1/share/clamav.
ClamAV comes with freshclam, a tool which periodically checks for new database releases and keeps your database up to date.
The database files, pid files, and sockets are under: /var/lib/clamav/.
cld file: ClamAV local database.