2004 sl500 sat install
 

I just acquired a 2004 SL500 and believe that it is factory wired for satellite radio (sirius). I would like to install the sirius unit from the factory. However, I can't find any information as to where the connectors are hidden or when the unit should be mounted. All the links that would have helped are out dated. Is there anyone that can simply let me know where to look?
Thanks in advance.