You would have to break the law in order to program your radio to listen to that system due to the issue with the system key, which falls under the definition of an unauthorized "access device" under Federal law. Even if you made your own key with a hex editor, it's still an unauthorized access device.
Get a scanner.
Using a Moto radio to monitor a Moto trunking system is opening up a huge can of worms that you do not want opened.
DO NOT DO IT. YOU WOULD BE A FOOL. I can not warn you more strongly than that via the internet.
Elroy