Diver, I'm a bit late to this posting, have not logged on for some time since we were in the middle of winter here in the northeast and ...
Anyway the pictures from other replies are great but I'd suggest taking a look at a posting from a number of years ago as well.
More than a few years ago I pulled my swing keel and had to learn about the way it is held in. I've done it twice now and it is relatively simple.
One of the best posts was made by .. Joe, Owner of Trinkka, an O'Day 222
Those who have been on the site will remember Joe for all the information he shared,
Unfortunately he passed away but the legacy of his spirit and his posting and advice are still available for all
You can read one of his posts with pictures of the various parts here.
http://forums.sailboatowners.com/index.php?threads/keel-is-stuck.143056/#post-936339
As stated by earlier responses getting the wedges out can be a bit of a challenge depending on what the previous owner used to hold them in. I used a hacksaw blade.
And yes that 60 lbs can be a chore when you are flat on your back on the ground trying to get everything aligned before you put the wedges in and tighten the plates. I used a couple of shingles to wedge the board in place and help keep it aligned once I thought it was in the right place. And yes I put a support under the board while I installed the wedges.
If you have not done it yet perhaps you can take some pictures as you do it and show other people how you did it.
James