Okay this is going to be one of those questions that may have been answered but in my mind it works.
I don't have a sketch but just think about it.
The water goes out the overflow down towards the sump. At the sump the down pipe attaches somewhere at the sump itself. At that point it's up to us to figure out how we want the water to dump into the sump itself.
Now a problem that I'm having (and I'm sure that some other people have the same problem) is bubbles coming out. Those bubbles are just a nuisance because they usually just pop and pop and pop to the point that they get water all over (on top of that they are probably part of the whole evaporation cycle).
I was thinking that if you went through and went straight down from where the pipe attaches to the sump, make a 90 degree angle into a much larger diameter pipe. Cut slots in the larger diameter on the bottom side of it to allow water to flow out. On the other end put a smaller diameter pipe that goes upwards again that would allow the trapped air that is at the top of the large diameter pipe to escape.
The bubbles are going to collect at the top of the large diameter because they want to go up. If they have a place to escape through they would collect not making small pops causing some evaporation because they would just collect in the tube, then have a place to allow the collected air to escape by having the tube on the other end.
Now at the top of that tube you would deffinately have to have a way to allow water to escape in case it decided to plug up for some unknown reason.