You can get a spigot for a 5 gallon bucket that will work on the curve. Try the San Antonio Homebrew Supply store on St. Mary's street. They should have them. If not, you can order one from pretty much any homebrew supplier online. I guess you just need to make sure the in flow into the bucket is no faster than the flow out of the bucket.

I haven't built my fuge yet (I'll be doing it this week, though), but the way I understand it is that you don't want too much flow in the fuge anyway. Just enough to keep it from being stagnant. You could put the spigot near the top of the bucket so that it is higher than the sump's water level. I would think that would work.