What I think you would need is some fixture to guide a chainsaw to cut a kerf through the middle. Then you can use the wedges as mentioned. I've seen an Alaskan mill, but they seem to hold the bar on the opposite side, which you can't as you need to make a blind cut 3/4 of the way through the log along it's length. I've never tried something like that by hand. I wonder if it would kickback?
