Reply to hooking up s4 into djm900 nexus

I will be djing in a club on thursday that has a house set up of 2 cdj900s and a djm 900nexus. I have a kontrol s4 and would like to use it, as I do not have tsp2 only tp2 at the moment. Can i bypass the soundcard of the djm and use the s4's soundcard by running RCA into a channel on the mixer or should I go from my audio port in my macbook to an rca input on the djm?

Also will my mappings for my s4 and x1 stay ok with the djm being a plug and play device for traktor? Thanks in advance for all the help.