It doesn't look like the BCD536 will show the System ID and WACN when holding on the control channel. It will only display "P25 and the NAC" in a flashing mode. The analyze function can be utilized to see the System ID and the WACN, but the system must be programed into the scanner with a name that can be used for the analyze function. An SDS 100 or 200 will show the System ID but not the WACN.
I am planning on adding this system to the RR database with the information that I have so far. I'll probably have it online sometime tomorrow, with a title of something like "City of Twin Falls". Corrections/additions to would be appreciated.