I was hoping to bait MacyBaby, as I've read a lot of what she has to say, which is extremely helpful.
This is definitely a top-clamping Kenmore rotary. The buttonholer does, in fact, attach directly to the bar, without the top clamp. That lead me to believe it would be possible to attach another type of low shank foot to it that was not necessarily top clamping. I would be willing to try a side clamping foot on it if it is possible to attach one. I mean, I've never FMQ'd before, so it's not like I'll know any better.