People have asked, “Is that even possible?” Yes, it is.
I did this remotely from work via ssh on my home box, worked fine, except for a speed bump here and there. Issues that were caused mainly by me not paying attention.
First off, make sure you upgradepkg pkgtools, gzip, and tar. Then install the xz package if its not already installed. If it is, then upgradepkg xz as well.
After that, you should be able to upgradepkg */*.tgz and then upgradepkg */*.txz to make sure everything gets added.
Now, the other issue is the 32bit compat libs that come with Slamd64. You will want to remove these.
You can get the latest release of the 32bit compat libs that Fred is working on here
Now, this is the process that worked for me and your mileage may vary. My upgrade path went a little differently than this and luckily I had a Slamd64 chroot available to symlink missing commands against or I would’ve been hosed.
Comments/suggestions, as always, are welcome.