If you have an audio panel with the appropriate connection, it's dead easy. There's a 3.5mm jack socket on the panel somewhere (usually marked Music) - a lead from that to the iPod and you're all set.
If you have a headset with the interface, it's similar.
Otherwise, forget it - for the pilot, at least. You don't want to miss important comms because you're listening to music.
I built (for a friend) an "interface box" to connect an iPod to headsets and mix the comm audio with the music - but strictly for pax use only. (I don't have any immediate plans to build any more.)
it is an old 1986 Piper Warrior so not sure if it would have that port.. I have a Bose AVIATION X headset. Does that have the interface for music?
Thanks