What options do I have if I want to keep my head unit (Pioneer) and control mp3 player from it? May be somebody have pictures of installs?

Guy from magnolia hifi told me they can put iPod, but I am not sure if it can be controlled from headunit (that have changer controls).

 

i dont think the head unit could control it

I know both blaupunkt and kenwood have hard drive MP3 players, but they need to be used with there changer controling head units