FreeBSD requires a little more editing than a single drop in file like Ubuntu.
These instructions will start with how to use csup to update your source and ports source trees, then configure your ports system to use our local repository for source downloads.
For all three revisions of FreeBSD available today, you can use the following command lines to update the source trees as root.
csup -h cvsup-freebsd.iphouse.net /usr/share/examples/cvsup/stable-supfile csup -h cvsup-freebsd.iphouse.net /usr/share/examples/cvsup/ports-supfile
To use the local repository to download files for any ports you are building (or installing via pkg_add -r) just update /etc/make.conf and add the following lines of code but keep a close eye on the FreeBSD version you are using. Bad things happen if you try to use the wrong versions!
FreeBSD 9 addition to /etc/make.conf
MASTER_SITE_BACKUP?= http://mirrors.iphouse.net/pub/FreeBSD/distfiles/${DIST_SUBDIR}/
MASTER_SITE_OVERRIDE?= ${MASTER_SITE_BACKUP}
PACKAGESITE=http://mirrors.iphouse.net/pub/FreeBSD/ports/amd64/packages-9-stable/Latest/
FreeBSD 8 addition to /etc/make.conf
MASTER_SITE_BACKUP?= http://mirrors.iphouse.net/pub/FreeBSD/distfiles/${DIST_SUBDIR}/
MASTER_SITE_OVERRIDE?= ${MASTER_SITE_BACKUP}
PACKAGESITE=http://mirrors.iphouse.net/pub/FreeBSD/ports/amd64/packages-8-stable/Latest/
FreeBSD 7 addition to /etc/make.conf
MASTER_SITE_BACKUP?= http://mirrors.iphouse.net/pub/FreeBSD/distfiles/${DIST_SUBDIR}/
MASTER_SITE_OVERRIDE?= ${MASTER_SITE_BACKUP}
PACKAGESITE=http://mirrors.iphouse.net/pub/FreeBSD/ports/amd64/packages-7-stable/Latest/