unfortunately the CSP radio system's zones cover odd shaped and relatively small areas. The scanner will only accept a radius around a single point for each system.
The problem I ran into trying to set up mine AND still keep the scan time under 5 seconds, was overlap with other zones, different traffic on several zones, and the size of the coverage area of each zone (especially the Intellirepeater Sites).
I finally gave up until the radio will accept user generated coverage shapes/sizes
chris