Using portsnap after sysinstall

[alex at schnarff.com]

I'm a longtime OpenBSD user admin'ing my first FreeBSD box. During 
installation of the system (6.2-RELEASE), I saw the option to add the 
ports tree and did so, figuring it made sense to add at that point 
since I'd definitely be using it later. Unfortunatley, I've just now 
discovered -- after installing several ports from my sysinstall'd tree 
-- that this installed an old version of the ports free, from when this 
version of FreeBSD was released. This is a problem because I need newer 
versions of some of the ports than is currently available, and I'm not 
sure how to proceed.

What I'd really like to be able to do is used portsnap, which seems 
like a great tool, but preserve all of the information about my 
existing packages. I have no idea if I can just wipe out my old 
/usr/ports and run "portsnap extract" (I've already run "portsnap 
fetch"), or if doing so would break my ports DB, dependencies, or 
something else I'm not familiar with.

If this isn't possible, what's the simplest way of updating to the 
latest version of a given port, or even the latest version of all ports 
(if that can be done), before installing? I know I can upgrade an 
already-installed version of a port with portupgrade, but as I 
understand it, this won't help me if I have an old version of the ports 
tree, as it appears to determine whether a port is old based on the 
info in the tree.

Thanks,
Alex Kirk