Haha, now that looks pretty cool.
There’s no way you can use the reguluar foot switch control on the S4 with this thing, the S4 takes a 1/4″ TS footswitch input which is a max of one switch.
However, you could plug this thing using the 5-pin DIN MIDI cables from the footswitch(s) to the the S4, making use of the MIDI ports on there. You’ll then have to custom map each footswitch control to what you want it to do on Traktor, but with 12 switches and 2 expression pedals, I think you could have something crazy going with effects there!
Also, check out DubFX on the NI Youtube channel – there’s a good video of him using footswitches to the max there!
(Actually, check out DubFX in general. He’s amazing!)