Well, instant gratification got the better of me, and I've answered my own question. :-/
It seems that this router (the Makita RT0701C) isn't that easy to modify. The top of the shaft isn't exposed, as is usually the case. Instead, it seems the tip of the shaft and the bearings are under another layer of plastic. Or perhaps that's not the bearings, but the "sender" part of what looks like a magnetic rotation sensor of some sort. Either way, I'm reluctant to disassemble further. Since I can't return the router to the local big-box anymore, I guess I'll mount it up and use it with its built-in variable speed (10K to 30K) for now, and perhaps get a Super-PID and mount the sensor down low near the collet. It looks like there's plenty of room there.
paul