As I stated, I have only -played- with SSH VPNs, I have not ever used one in production. For production, these days, I am using IPSec.
A discussion of SSH VPNs, including syntax, can be found right in the
ssh(1) man page, under the section called
SSH-BASED VIRTUAL PRIVATE NETWORKS. There's another example in the
OpenBSD Journal, which uses the ssh configuration files to eliminate the need for -w.
Additional details of SSH VPN were discussed in an interview Damien Miller gave to
SecurityFocus when OpenSSH 4.3 was about to be released.