Unfortunately I do not see an article for 8.x, but I can tell you that the 7.x article will be very similar to the process for 8.x. The main differences will be how you create the ISAKMP acl rule and how you modify the ISAKMP server settings.
the example on Frank Oswood's page works great and I tried that before. If you take a look at the example in VPN Definitions the VPN is terminated in the "Internal" zone. In my opinion and from a security stand point is not a very reliable configuration because you can't enforce any policy to VPN users. If you terminate VPN tunnels in a "VPN Zone" you have to configure rules to allow connections to Internal or other zones in the firewall and then you enforce policies to VPN users.