Correct MIDI settings for CDj 2000 & Traktor

Hi
In the past i have encountered problems in hooking in my Mac running Traktor where by the sound from the 2 decks will come out of one channel and it takes so long to get it working. i dont want to turn up at a gig and have to fiddle around for ages and ages especially if in following another dj.

Can you please tell me what the correct settings for Midi should be for this. and also whats the best practice in future to avoid having to do this all them time.

apologies if it has been posted before