The ISO images for the basic release CDs are available via BitTorrent. A collection of torrent files to download the images is available at http://torrents.freebsd.org:8080
The BitTorrent client software is available from the net-p2p/py-bittorrent port, or a precompiled package.
After downloading the ISO image with BitTorrent, you may burn it to CD or DVD media as described in Section 19.6.3, burncd.