yeah the DJM's RCA outputs can be connected to wherever the iPod was plugged into (as long as it's an RCA at the "bar" end) what you should do is start with the master level low... then slowly increase the master level to find the exact limit where the audio distorts on the bar's system- match that with the meters on the mixer (+3dB usually safe) and try not to go over that during the night.
Good luck!