Here's where I'm at so far. (Pics below)
I used my dremel to trim down the tongue to fit between the new mount. (I did make my own mount but it was past midnight and way too late for pictures)
I was at a loss for what to use to keep the bolts in place (mostly b/c we still live in an apartment and I don't have room for scraps of metal and such) and then came across the idea to use the aluminum from the side of a computer case.
I cut a smaller piece to go between the cushion and the seat pan, and then a larger piece to go between the seat pan and the frame. I then bolted the two pieces together and used a 2 1/2 inch 3/8 bolt to shoot down through the frame to mount the seat to the bike.
I was pretty keen to finish it last night b/c we were expecting rain the rest of this week, so I got a pic of it in the dark. I have leather saddlebags that I'm going to put back on, but I have to wait to see how it will all look with the Honda 1100 sissy bar and what other adjustments I'll need to make.
For now, though, the seat is on and secure.
@Chuck A. I found for some reason on mine I didn't need to add anything to the cross beam behind the battery b/c the rubber stoppers actually rested on the beam. But I do have plans to put a support across the back where the passenger will sit b/c those are just free floating about 1/2 inch above the frame.
The sissy bar is supposed to come tomorrow, and we'll see how much I get done before I have to leave for the weekend.