Im not going to say there is not a way using code, but I will stand on John Chambers coffee table and tell him the only way to do this is via physical load balancing.
This requires smaller cells using data rates no lower than 11mbps and lower power settings. By limiting the cell (and adding more AP's to fix the subsequent holes) you will physically load balance the network. Turn RRM off. hard code the channels and power.
Depending on size of area and number of users, I would attempt to stick three AP's in your scenario with really small cell sizes that whose boundaries are no worse than -65dBm. When I have tweaked enough to roam from edge to middle to the other edge of the room and hit all three AP's based on location..you should be good. Directional antennas also would play an important role here as well, shining down from the ceiling with radiation patterns kind of like spotlights. Also you would have to turn the power down on the clients or else you just have the same problem except it is now upside down.
Aggresive load balancing tends to jack up phones and possibly create a 'host flapping' situation with data clients as well. I do not use it at all.
good luck-
