Don't bother; It's a trunked system, and unfortunately, it's encrypted 100% of the time. There is no way you will be able to monitor these agencies anymore, unless you are an employee of one of the departments, and carry a Cook County-issued radio on that network.
GOOD! Now I won't have to worry about hearing them when I listen to Lake Zurich on my car scanner which does not support CTCSS or DCS Codes. Lake Zurich uses 470.7375 and so did blue island, just with a different pl code.