Volvo Repair: 2005 S80 AWD, diy project, homelink

Question
The vehicle did not come with homelink on the driver's visor and I would like to add it.  Can I just buy an OEM visor with homelink, remove the old, and install the new? Or, does this require a software upgrade of some sort?  Also, I would like to add an OEM cd changer in the trunk that will be controlled by the factory installed headunit (model HU650).  Is this a DIY project or dealer only?  Does it require software changes to the car?  How can I tell if the car is prewired to accept the Volvo changer?  Thanks in advance for your time and knowledge.

Answer
Steven, anything on these cars require downloads.  The homelink definately needs a program download.  Dealer.  If its prewired in will be in the trunk comparments on either the left or right side.  Not sure about the download for the changer.  I would call the dealer on that one.  Roger