On my old EOS-3, I had the custom function set to only AF when I pressed the asterisk button, I think it was. I had the shutter half-depress set to exposure lock, and finger OFF the asterisk be focus lock.Wouldn't Eye controlled focus make framing a bit more difficult, or at least make the focus wander all around the frame while you check the framing?
It worked great on the EOS-3 and I have no idea why they then discontinued it. It was especially important for focusing off-center subjects. Instead of bothering moving the cursor on my EOS-1-whatevers, I'd focus-recompose-shoot, but unless the plane of focus were spherical or DOF pretty thick, that basically doesn't work great. (I did it anyway but got lots of unusable shots that way, but still never learned to like manually moving the focus point around.).