Hi,
The CMX REST API resources are what you need, see the learning labs under the CMX tag Cisco DevNet Learning Labs. The CMX sandbox GUI provides a lot of information about the location services available, but the REST API is needed for designing networked applications. The CMX sandbox is running a simulation of the Wireless Lan Controller (WLC) which provides 80 active wireless clients, moving with in the floors of DevNetCampus and the CiscoCampus. The floor of CiscoLiveLatAm currently has no APs configured and therefore no wireless client tracking.
Matt