So in the file APL\NDeviceLib.dll there are several very interesting references in the .rdata section (open the file with 7zip and use a hex editor like Notepad++ w/ Hex Editor plugin, "F4" in 7zip is your friend here):

 

SendNaviSourceSwitchReq@NPuComHandlerProxyBase

InstanceBase@NPRmtCtrlHandlerProxy

IsChangeFlg@NPuComMemoryBase

OffWait@NPuComMemoryBase

OnPostEvent@NPRmtCtrlHandlerProxyBase

OnPostEvent@NPuComHandlerProxy

 

Looks to me like this DLL has the library routines to talk to the uCOM, request audio source switching and handle Remote Control commands... I don't have IDA Pro at the moment (and next to no free time to use it even if I did) but would be very interested to see what the .text section reveals. Anyone w/ IDAPro mind taking a crack at this file and post what you find?