Yes, do as Nick says and you should hear them. Actually, St Ann is one of the more active users on this new system.
Hook your new 436 to a computer and install Sentinel.
Read the scanner first if you have done any custom favorite lists.
Once read, do the check for HPDB database updates.
Let that finish and then look under Missouri/St Louis (not city) and then county systems and you will see one for SLATER.
Right click that one and add it to your favorites.
It's more complicated then it sounds but once you get the hang of it, it starts becoming easier!
The only problem I have is when the SLATER DB is updated here, I must append the new data to my customized SLATER favorite list and then copy and paste anything new into my customized Slater favorite.
Being a new and growing system, there are usually weekly updates and it will probably be a while before the system is fully functional with everyone on it.
Or... you could just import Slater each time as a new favorite and remove the old one. If you have not customized any names, that would make sure you have the latest updates and talkgroups.
If you tried to program St Ann's old V/UHF frequencies, you will not hear anything as they have now vacated those old channels. All their comms are on the new P25 digital system.
Each town or city also has a car to car or TAC type channel available to them. Those will be encrypted and you will not hear them but for general dispatch, all PD is in the clear so far with the exception of all Law channels in Jefferson County. They started out encrypted and it looks like they have no intent of going to a clear mode for even simple dispatch.