DNX9140 aux?

is it just not possible? its a PITA for other people in my car to get hooked in to the head unit. I know they make a cable (KC310V or something) but it's for older iPods, I just want to be able to plug in any 3.5mm jack source.
I can get the 2 male end 3.5mm cable and use that, but is that possible? I removed the head unit once and tried it, but it didn't seem to work on any of the options.
Thanks.






