Update:
Finally got around to working on this today. Thought I'd update with results, for future users that might have the same issue.
I messed around a little bit trying to create a spout with flashing. That might have worked, but I couldn't really figure out how to camouflage it well, and I wasn't patient enough to let the silicone dry. So, after spending another hour looking around on the web, and basically finding nothing, I decided to bravely go where no man has gone before (at least, not with internet documentation).
First my research revealed that a straight, flat edge was what I was looking for to get the best pour effect. There's lots of water features you can buy that replicate this, but I've got fancy pots already, so why not try to break them first, before I bought the new ones?
I took an empty ceramic pot from the wife's stash beside the house, and made some practice cuts. I used a cutoff wheel attached to my trusty die grinder (air powered--I recommend against using electric power tools while working on the edge of the pool). The test cuts worked well, so off to the back yard.
I used a small level to mark a horizontal line with a sharpie on the lip of the pot at the approximate width I wanted to cut. I made my width about an inch narrower on each side of the lip from where the water level was when the pot was full. I figured I could always cut more off, but adding back would be a challenge. After marking out the horizontal lines, I drew in and cut my vertical cuts, stopping just short of my horizontal line. I then scored the horizontal line, and made a plunge cut in the center, gently working the cut out to the two verticals, but being careful not to pass them. Also use care on the horizontal cuts to keep the cutoff wheel parallel to the ground, rather than perpendicular to the axis of the pot lip. Not sure whether that would cause a big problem or not, but the water seemed to flow better when the cut was parallel to the ground, or slightly sloped down toward the drop off, and smooth. I used the level to ensure the horizontal cut was square and level. If you don't get the cut level, the water will twist as it pours, which was kinda neat, but not the effect I was looking for.
The first two pots I set the horizontal line even with the top of the pot lip at its lowest point, so that I was essentially only cutting out two triangles out from the center mark. This worked well on those two, but the last pot had a different contour to the lip, so that there was still a slope to the pot lip going away from the cut (hard to describe; essentially once the water flowed past the cut, it still had ceramic to run off, before the lip fell away). I ended up cutting deeper until I had removed the lip (again, so the water dropped off when it reached the edge of the cut).
Here are some pics of the finished product. I hope this helps somebody else.
This last picture shows that I still have some cleanup work to do, although it's impossible to see when the water's flowing, which it normally is. I still need to find out what kind of coating is necessary, if any, to protect the cut area, since the glaze is gone.
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