Locker rooms usually exhaust directly outside (no return to the a/c unit) so you should not be condensing any of the humidity to have a latent load. ASHRAE table 7 of chapter 6 of the 2007 HVAC Applications recommends .5 cfm/ft2 for a ventilation rate. The latent load would depend on your makeup air for this exhaust rate. My Cooks "Engineering Cookbook" recommends an air change in locker rooms every 2-5 minutes.
Gepman is right, you shouldn't be worried about treating the latent loads in a locker room, you should be exhausting it. If you increase the exhaust rate by increasing the fan speed (if it can do it) and rebalancing the system to exhaust more from the locker room. You might consider ducting an additional fan if you have the option. Or perhaps the room itself needs a good adjustment for the exhaust to be utilized in the best manner.
