Adapted from gentoo forum...
1. ) On the Gentoo machine, edit make.conf and change SYNC to:
SYNC="rsync://localhost:4040/gentoo-portage"
2.) Make an ssh tunnel from your Gentoo box to the remote box to go to rsync.gentoo.org, i.e.
ssh -L 4040:rsync.gentoo.org:873 remote.host.com
3.) Now rsync as usual from another prompt:
emerge --sync
Instead of editing make.conf, we can use "export" to set SYNC environment variable before emerge --sync too.
