So you're thinking of a trickle filter or wet/dry. You can do that.
You'd fill that first chamber with your bioballs with the idea of the bioballs being above the water line. Here are examples:
http://www.f3images.com/IMD/600/CR1311/CR1311_99.jpg
http://www.f3images.com/IMD/600/YPM5153/YPM5153_99.jpg
The water comes through the top of the first chamber. The water hits an acrylic plate drilled with lots of holes to disperse the water to maximize the coverage over the bioballs. The bioballs are elevated by another shelf (eggcrate would probably work). The water trickles down the bioballs and under the baffle into the next chamber.
You could follow that same setup, but I think you could just as well use about any sump design and pour in your bioballs as long as you have water movement through them.
FYI, bioballs can lead to nitrate issues rather than just LR. LR has deep pores and anaerobic areas that allow for the complete waste cycle to occur. Bioballs are very efficient, and converts waste very quickly. However, without the deep anaerobic areas, bioballs don't complete the processing of waste and stops at nitrates. Just wanted to make sure you understand that.
Bioballs are about the only way to go with FO setups, and they can work on FOWLR, but aren't a good idea for reefs because of the nitrate issue.
As for KC, surely someone has base rock.
It's been a couple of years since last visiting a few LFS in KC, but one I alwasy tried to stop in at was Paradise Aquatics in Overland Park. There was also place in the city, and now the name escapes me - it was north of the Westport area and over a few block around Main St. A lot of help, huh?
Anyway, there is a KC fish group, and getting plugged in with other hobbyists is always helpful. There is also a KC area Web site that may also help you:
http://fishheads.org/